JP2019533377A - Efficient multiplexing of control information in transport blocks - Google Patents

Abstract

The data transmission node of the present disclosure receives, from the third layer, at least one second layer service data unit (SDU) that is mapped to resources allocated for data transmission, and at least one second layer SDU. And a second layer processing circuit for generating a second layer protocol data unit (PDU) including at least one second layer control element arranged after any of the at least one second layer SDU, and a second layer processing A first layer processing circuit that receives the second layer PDU generated by the circuit and maps the second layer PDU to a resource allocated for data transmission.

Description

  The present disclosure relates to transmission and reception processing on a plurality of layers in a communication system, as well as a corresponding transmission apparatus, method, and program.

  Third generation mobile communication systems (3G) based on WCDMA® radio access technology are being deployed on a wide scale around the world. High-speed downlink packet access (HSDPA) and high-speed uplink packet access (HSUPA) are the first steps in enhancing or evolving this technology. An enhanced uplink, also referred to as, has been introduced, thereby providing a highly competitive radio access technology. In order to meet the increasing demand from users and ensure competitiveness for new radio access technologies, 3GPP has introduced a new mobile communication system called Long Term Evolution (LTE). LTE is designed to provide the carrier required for high speed data and media transport and high capacity voice support over the next decade. The ability to provide high bit rates is an important strategy in LTE. E-UTRA (Evolved UMTS Terrestrial Radio Access (UTRA)) and UTRAN (UMTS Terrestrial Radio Access Network) work items (WI: Work Item) specifications for LTE (WI: Work Item 8) are finally released as TE. Published. The LTE system is a packet-based efficient radio access and radio access network that provides all IP-based functions with low latency and low cost. In LTE, to achieve a flexible system deployment using a given spectrum, multiple transmit bandwidths (eg, 1.4 MHz, 3.0 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz, And 20.0 MHz) are specified. In the downlink, radio access based on orthogonal frequency division multiplexing (OFDM) is employed. This is because such a radio access is inherently less susceptible to multipath interference (MPI) due to its low symbol rate, uses a cyclic prefix (CP), and has various transmission bandwidths. This is because the width configuration can be supported. For the uplink, radio access based on single-carrier frequency division multiple access (SC-FDMA) is employed. This is because, given the limited transmission output of user equipment (UE: User Equipment), priority is given to providing a wider coverage area than improving the peak data rate. LTE Rel. In FIG. 8, a number of major packet radio access technologies (for example, MIMO (Multiple Input Multiple Output) channel transmission technology) are adopted, and a highly efficient control signaling structure is realized.

<LTE architecture>
The overall architecture is shown in FIG. 1, and a more detailed depiction of the E-UTRAN architecture is given in FIG. E-UTRAN consists of eNBs, which terminate E-UTRA user plane (PDCP / RLC / MAC / PHY) and control plane (RRC) protocols for UEs. The eNB includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data control protocol (PDCP) layer (these). The layer hosts user plane header compression and encryption functions). The eNB also provides a radio resource control (RRC) function corresponding to the control plane. eNB performs radio resource management, admission control, scheduling, negotiated uplink (UL) quality of service (QoS), broadcast of cell information, encryption / decryption of user plane data and control plane data, It performs many functions, such as compression / decompression of downlink (DL) / uplink (UL) user plane packet headers. The plurality of eNBs are connected to each other by an X2 interface. In addition, the plurality of eNBs are provided by EPC (Evolved Packet Core) through the S1 interface, more specifically, MME (Mobility Management Entity) through S1-MME, and Serving Gateway (S-GW: Serving through S1-U). (Gateway). The S1 interface supports a many-to-many relationship between the MME / serving gateway and the eNB. While SGW routes and forwards user data packets, it functions as a mobility anchor for the user plane at the time of handover between eNBs, and also an anchor for mobility between LTE and other 3GPP technologies (S4 It terminates the interface and relays traffic between the 2G / 3G system and the PDN GW). The SGW terminates the DL data path for the idle UE, and triggers paging when DL data arrives at the UE. The SGW manages and stores UE context (eg, IP bearer service parameters or network internal routing information). In addition, in the case of lawful interception, replication of user traffic is executed.

  The MME is the main control node of the LTE access network. The MME is responsible for idle mode UE tracking and paging procedures (including retransmissions). The MME is involved in the bearer activation / deactivation process, and also at the UE's SGW during the initial attach and during intra-LTE handover with core network (CN) node relocation. Also plays a role of selecting. Also responsible for authenticating the user (by interacting with the HSS). Non-Access Stratum (NAS) signaling is terminated at the MME. The MME also plays a role of generating a temporary ID and assigning it to the UE. The MME checks the UE's authentication to enter the service provider's Public Land Mobile Network (PLMN) and enforces the roaming constraints of the UE. The MME is a termination point in the network for encryption / integrity protection of NAS signaling, and manages security keys. Lawful interception of signaling is also supported by the MME. The MME also provides a control plane function for mobility between the LTE access network and the 2G / 3G access network and terminates the S3 interface from the SGSN. Furthermore, the MME terminates the S6a interface towards the home HSS for the roaming UE.

  The downlink component carrier of 3GPP LTE system is further divided in the time-frequency domain in so-called subframes. In 3GPP LTE, each subframe is divided into two downlink slots. The first downlink slot comprises a control channel region (PDCCH region) in the first OFDM symbol. Each subframe consists of a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Rel. 8)), and each OFDM symbol extends over the entire bandwidth of the component carrier. Thus, each OFDM symbol consists of a number of modulation symbols transmitted on each subcarrier.

  For example, assuming a multi-carrier communication system using OFDM or the like used in 3GPP Long Term Evolution (LTE), the smallest unit of resources that can be allocated by the scheduler is one “resource block”. A physical resource block (PRB) is defined as continuous OFDM symbols in the time domain (eg, 7 OFDM symbols) and continuous subcarriers in the frequency domain (eg, 12 subcarriers of the component carrier). Is done. Therefore, in 3GPP LTE (Rel. 8), a physical resource block is composed of resource elements and corresponds to one slot in the time domain and 180 kHz in the frequency domain (for further details on the downlink resource grid, see, for example, Section 6.2 (available at http://www.3gpp.org and incorporated herein).

  One subframe consists of two slots. There are 14 OFDM symbols in a subframe when a so-called “normal” CP (cyclic prefix) is used, and 12 in a subframe when a so-called “extended” CP is used. OFDM symbols exist. For the purposes of terminology, in the following, the equivalent time-frequency resources for the same continuous subcarriers extending throughout the subframe are referred to as “resource block pair” or equivalent “RB pair” or “PRB”. This is referred to as a “pair (PRB pair)”.

  The term “component carrier” refers to a combination of several resource blocks in the frequency domain. In a future release of LTE, the term “component carrier” will no longer be used, but instead the terminology will be changed to “cell”, which represents a combination of downlink resources and optionally uplink resources. Linking between the carrier frequency of the downlink resource and the carrier frequency of the uplink resource is specified in the system information transmitted on the downlink resource. Similar assumptions regarding the component carrier structure apply to subsequent releases.

<Overview of OSI layer>
FIG. 3A gives an overview of the layer model on which the LTE architecture is detailed.

  The Open Systems Interconnection (OSI) reference model (OSI model or OSI reference model) is a layered abstract description for communication and computer network protocol design. The OSI model divides system functionality into a series of layers. Each layer has the property of using only the functions of the lower layer and exporting the functions to the upper layer. A system that implements a protocol behavior consisting of a series of these layers is known as a “protocol stack” or “stack”. Its main feature lies in the connection between layers and defines the specifications for the interaction method between layers. This means that a layer written by one manufacturer can work with a layer by another manufacturer. For the purposes of this disclosure, only the first three layers are described in more detail below.

  The primary purpose of the physical layer or layer 1 is the transmission of information (bits) over a specific physical medium (eg, coaxial cable, twisted pair cable, optical fiber, air interface, etc.). This converts or modulates the data into signals (or symbols) that are transmitted on the communication channel.

  The purpose of the data link layer (ie, layer 2) is to divide the input data into data frames (segmentation and reassembly (SAR) function) so as to adapt to the specific physical layer. It is to shape the information flow. Furthermore, potential transmission errors may be detected and corrected by requesting retransmission of lost frames. This typically provides an addressing mechanism and can provide a flow control algorithm to match the data rate with the receiver capacity. When multiple transmitters and receivers use a shared medium simultaneously, the data link layer typically provides a mechanism for regulating and controlling access to the physical medium.

  The data link layer is often subdivided into sub-layers (e.g., UMTS RLC and MAC layers) to provide many functions. Typical examples of layer 2 protocols are PPP / HDLC, ATM, frame relay and RLC, LLC or MAC for wireless systems for fixed line networks. Detailed information regarding the layer 2 sub-layers PDCP, RLC, and MAC will be described later. In the present application, since the sub-layer is also referred to as “layer”, the term “layer” used in this specification does not necessarily mean a layer of the OSI model.

  Network layer or layer 3 provides functional and procedural means to transmit variable length packets from source to destination over one or more networks while maintaining the quality of service required by the transport layer To do. Usually, the main purpose of the network layer is, among other things, to perform network routing, network partitioning, and congestion control functions. Major examples of network layer protocols are IP (Internet Protocol) or X.264. 25.

  Regarding layers 4-7, it should be noted that applications and services may make it difficult to tie an application or service to a particular layer of the OSI model. This is because applications and services that operate above layer 3 often perform various functions tied to different layers of the OSI model. Therefore, particularly in a TCP (UDP) / IP-based network, the so-called “application layer” may be configured by combining the layer 4 and the layer above it.

<Layer service and data exchange>
Hereinafter, the terms service data unit (SDU) and protocol data unit (PDU) as used herein are defined with respect to FIG. 3B. SDU and PDU entities have been introduced to formally describe the packet exchange between layers of the OSI model. The SDU is a unit of information (data / information block) transmitted from a layer N + 1 protocol that requests a service to a protocol in the layer N via a so-called service access point (SAP). A PDU is a unit of information exchanged between peer processes at the same protocol transmitter and receiver at the same layer N.

  A PDU is typically formed by a payload portion that consists of a specific header at layer N followed by optionally processing a received SDU that is terminated by a trailer. Since there is no direct physical connection between these peer processes (except for Layer 1), the PDU is forwarded to Layer N-1 for processing. Therefore, the layer N PDU is an SDU from the viewpoint of the layer N-1.

<LTE User Plane (UP (U-Plane)) and Control Plane (CP (C-Plane) Protocol)>
The LTE layer 2 user plane / control plane protocol stack includes three sublayers: PDCP, RLC, and MAC.

  As described above, on the transmission side, each layer receives SDUs from higher layers that provide services, and outputs PDUs to lower layers. The RLC layer receives packets from the PDCP layer. These packets are referred to as PDCP PDUs from the PDCP point of view, and represent RLC SDUs from the RLC point of view. The RLC layer generates packets that are provided to the lower or MAC layer. Packets provided to the MAC layer by RLC are RLC PDUs from the RLC point of view and MAC SDUs from the MAC point of view. On the receiving side, the process is reversed and each layer passes the SDU to the upper layer where it is received as a PDU.

  While the physical layer inherently provides a bit pipe protected by turbo coding and cyclic redundancy check (CRC), link layer protocols provide services to higher layers with improved reliability, security, and integrity. To strengthen. The link layer is also responsible for multi-user medium access and scheduling. One of the major challenges of LTE link layer design is to provide the required reliability level and delay for Internet Protocol (IP) data flows with a wide variety of services and data rates. In particular, protocol overhead scaling is required. For example, it is widely assumed that voice over IP (VoIP) flows can tolerate delays on the order of 100 ms and packet loss of up to 1 percent. On the other hand, it is well known that downloading of a TCP file is performed well on a link of a product with a small bandwidth delay. As a result, downloading at very high data rates (eg, 100 Mb / s) requires further delay suppression and is more susceptible to IP packet loss than VoIP traffic.

  The above is generally achieved by three sublayers of the LTE link layer that are partially connected. The Packet Data Convergence Protocol (PDCP) sublayer is primarily responsible for compression and encryption of IP headers. It also supports low loss mobility in case of inter-eNB handover and provides integrity protection for higher layer control protocols. The radio link control (RLC) sublayer mainly has ARQ function and supports data division and concatenation. The latter two minimizes protocol overhead regardless of data rate. Finally, the medium access control (MAC) sublayer provides HARQ and performs functions necessary for medium access such as scheduling operation and random access.

  In particular, the medium access control (MAC) layer is the lowest sublayer in the layer 2 architecture of the LTE radio protocol stack, and is defined by, for example, Non-Patent Document 2, which is a 3GPP technology standard. The lower physical layer is connected through a transport channel, and the upper RLC layer is connected through a logical channel. Accordingly, the MAC layer performs multiplexing and demultiplexing between the logical channel and the transport channel. The MAC layer on the sending side builds MAC PDUs (also known as transport blocks) from the MAC SDUs received through the logical channel, and the MAC layer on the receiving side restores the MAC SDUs from the MAC PDUs received through the transport channel. To do.

  The MAC layer provides a data transmission service to the RLC layer through a logical channel (see Sections 5.4 and 5.3 of Non-Patent Document 3 incorporated herein), and this logical channel includes control data. Either a control logical channel carrying (eg, RRC signaling) or a traffic logical channel carrying user plane data. On the other hand, data from the MAC layer is exchanged with the physical layer through a transport channel (classified as downlink or uplink). Data is multiplexed into the transport channel according to the transmission method through the radio. In addition to the MAC SDU, the MAC PDU may further include a plurality of types of MAC control elements and padding as necessary.

  The physical layer is responsible for actually transmitting data and control information via the air interface. That is, the physical layer carries all information from the MAC transport channel on the air interface on the transmitting side. Some important functions performed by the physical layer include coding and modulation, link adaptation (AMC), power control, cell search (for initial synchronization and handover purposes), others for the RRC layer Measurement (inside the LTE system and between systems). The physical layer performs transmission based on transmission parameters (modulation scheme, coding rate (that is, modulation / coding scheme (MCS)), the number of physical resource blocks, and the like). Other information regarding the function of the physical layer is described in Non-Patent Document 4, which is a 3GPP technical standard, which is incorporated herein by reference.

  The radio resource control (RRC) layer controls the communication between the UE and the eNB at the radio interface and the mobility of the UE moving across multiple cells. The RRC protocol also supports transmission of NAS information. For RRC_IDLE UEs, RRC supports notification of incoming calls from the network. RRC connection control consists of all procedures related to establishing, changing and releasing RRC connections (paging, measurement setup and reporting, radio resource setup, initial security activation, signaling radio bearer (SRB) and Covers radio bearers carrying user data (including establishment of data radio bearers (DRBs)).

  The radio link control (RLC) sublayer has mainly ARQ function and supports data division and concatenation. That is, the RLC layer performs RLC SDU framing to the size indicated by the MAC layer. The latter two minimizes protocol overhead regardless of data rate. The RLC layer is connected to the MAC layer via a logical channel. Each logical channel carries a different type of traffic. The layer above the RLC layer is usually the PDCP layer, but in some cases it is the RRC layer. That is, the RRC message transmitted on the logical channels BCCH (broadcast control channel), PCCH (paging control channel), and CCCH (common control channel) does not require security protection. Passed directly.

<RLC retransmission protocol>
If the RLC is configured to request retransmission of a missing PDU, it can be said that the RLC is operating in an acknowledged mode (AM). This is similar to the corresponding mechanism used in WCDMA / HSPA. In general, RLC has three operation modes: a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode (AM). Each RLC entity is configured by RRC to operate in one of these modes.

  In transparent mode, no protocol overhead is added to RLC SDUs received from higher layers. In special cases, transmissions with limited split / reassembly capabilities can be achieved. Regardless of whether segmentation / reassembly is used, there is a need for negotiation in the radio bearer setup procedure. The transparent mode is used for a service that is very susceptible to delay, such as conversation.

  In unacknowledged mode, data delivery is not guaranteed because no retransmission protocol is used. The PDU structure includes a sequence number for integrity observation in higher layers. Based on the RLC sequence number, the receiving UM RLC entity can perform reordering of received RLC PDUs. Splitting and concatenation is effected by header fields added to the data. An RLC entity in unacknowledged mode is unidirectional because no relationship is defined between the uplink and the downlink. When erroneous data is received, the corresponding PDU is discarded or marked according to the setting. In the transmitter, RLC SDUs that are not transmitted within a certain time specified by the timer are discarded or deleted from the transmission buffer. RLC SDUs received from higher layers are divided / concatenated into RLC PDUs on the transmission side. On the receiving side, reassembly is performed correspondingly. Unacknowledged mode is used for services where there is no significant delivery error compared to short delivery times, such as cell broadcast services such as MBMS and Voice over IP (VoIP) in specific RRC signaling procedures.

  In the confirmation mode, the RLC layer supports error correction through an automatic repeat request (ARQ) protocol and is typically used for IP-based services such as file transmission where error-free data delivery is of primary concern. The RLC retransmission is based on, for example, an RLC status report received from a counterpart RLC receiving entity, ie ACK / NACK. The confirmation mode is designed for reliable transport of packet data through retransmissions in the presence of high bit error rates on the air interface. In the case of PDU error or loss, retransmission is executed by the transmission side upon reception of the RLC status report from the reception side.

  ARQ is used as a retransmission scheme for retransmitting erroneous or missing PDUs. For example, by monitoring incoming sequence numbers, the receiving RLC entity can identify missing PDUs. An RLC status report can then be generated on the receiving RLC side and fed back to the transmitting RLC entity to request retransmission of missing PDUs or PDUs that have failed to be decoded. Also, the RLC status report can be polled by the transmitter. That is, by using the polling function by the RLC transmitter, a status report is acquired from the RLC receiver side, and the reception buffer status is notified to the RLC transmitter. The status report provides acknowledgment (ACK) or negative acknowledgment information (NACK) or part of the RLC data PDU up to the last RLC data PDU for which HARQ reordering is completed. The RLC receiver triggers a status report when the polling field is set to “1” or when the RLC data PDU is detected as missing. Section 5.2.3 of Non-Patent Document 5 defines a specific trigger that triggers polling of the RLC status report in the RLC transmitter, which is incorporated herein. The transmitter can only transmit to PDUs in the transmission window, and the transmission window is updated only by the RLC status report. Therefore, if the RLC status report is delayed, the transmission window cannot be advanced and the transmission may be blocked. The receiver sends an RLC status report to the sender when triggered.

<Layer 1 / Layer 2 control signaling>
L1 / L2 control signaling is used for the purpose of notifying the scheduling target user of user allocation status, transport format, and other transmission-related information (for example, HARQ information, transmission power control (TPC) command). Sent on the downlink along with the data. L1 / L2 control signaling is multiplexed with downlink data within a subframe (assuming user allocation can vary from subframe to subframe). User assignment can also be performed on a TTI (transmission time interval) basis. Note that in that case, the TTI length may be an integer multiple of the subframe. The TTI length may be constant for all users in the service area, may be different for different users, or may be dynamic for each user. In general, the L1 / L2 control signaling may be transmitted once per TTI. In the following, it is assumed that TTI is equal to one subframe without loss of generality.

  L1 / L2 control signaling is transmitted on the physical downlink control channel (PDCCH). The PDCCH carries a message as downlink control information (DCI: Downlink Control Information). The DCI most often includes resource allocation to the mobile terminal or UE group and other control information. A plurality of PDCCHs can be transmitted in one subframe.

  In general, information sent by L1 / L2 control signaling for the purpose of allocating uplink radio resources or downlink radio resources (particularly LTE (-A) Rel. 10) can be classified into the following items.

  User identification information (User Identity): indicates a user to be assigned. This information is usually included in the checksum by masking the CRC with user identification information.

  Resource allocation information (Resource Allocation Information): indicates a resource (for example, a resource block (RB)) to which a user is allocated. Alternatively, this information is referred to as resource block assignment (RBA). Note that the number of RBs to which a user is assigned can be dynamic.

  Carrier indicator: used when the control channel transmitted on the first carrier allocates resources related to the second carrier, ie resources of the second carrier or resources related to the second carrier (Cross carrier scheduling).

  Modulation and coding scheme: Determines the modulation scheme and coding rate to be employed.

  HARQ information: New Data Indicator (NDI) and / or Redundancy Version (RV), etc. especially useful when retransmitting a data packet or part thereof.

  Power control command: Adjusts transmission power when transmitting uplink data or control information to be allocated.

  Reference signal information: applied cyclic shift and / or orthogonal cover code (OCC) index, etc. used for transmission or reception of reference signals associated with assignment.

  Uplink assignment index or downlink assignment index: Used to identify the order of assignment and is particularly useful in TDD systems.

  Hopping information: indicates, for example, whether and how to apply resource hopping for the purpose of increasing frequency diversity.

  CSI request: Used to trigger to send channel state information on the allocated resource.

  Multi-cluster information: Used to indicate and control whether to transmit in a single cluster (continuous set of RBs) or multi-cluster (at least two discontinuous sets of continuous RBs) Flag to be Multi-cluster assignment is based on 3GPP LTE- (A) Rel. 10 is introduced.

  It should be noted that the above list is not exhaustive and that depending on the DCI format used, it is not necessary to include all the aforementioned information items in each PDCCH transmission.

  Downlink control information occurs in multiple formats that differ in overall size and information contained in the aforementioned fields. The various DCI formats currently defined for LTE are as follows, and are available in Section 5.3.3.1 of Non-Patent Document 6 (http://www.3gpp.org). (Incorporated in the book). For example, the following DCI format can be used to carry uplink resource grants.

  Format 0: DCI format 0 is used for transmission of PUSCH resource grant, and uses single antenna port transmission in uplink transmission mode 1 or 2.

  Format 4: DCI format 4 is used for PUSCH scheduling, and uses closed-loop spatial multiplexing transmission in uplink transmission mode 2.

<LTE uplink access method>
According to the uplink scheme, both scheduling-based access (that is, control by eNB) and contention-based access are possible.

  For access by scheduling, the UE is assigned a specific frequency resource (ie, time / frequency resource) over a period of time for uplink data transmission. However, some time / frequency resources can be allocated for contention-based access. In these time / frequency resources, the UE can transmit without initial scheduling. One scenario where the UE performs contention-based access is, for example, the case where the UE performs random access, ie first access to a cell or first access requesting uplink resources.

  For access by scheduling, the eNodeB scheduler allocates unique frequency / time resources for uplink data transmission to users. More specifically, the scheduler determines which UE is allowed to transmit in which physical channel resource (frequency) and the corresponding transport format that the mobile terminal uses for transmission.

  The allocation information is communicated to the UE by being transmitted on the L1 / L2 control channel via a scheduling grant. The scheduling grant message includes information on the part of the frequency band that the UE is allowed to use, the validity period of the grant, and the transport format that the UE should use for the next uplink transmission. The shortest valid period is one subframe. Further, depending on the selected method, other information may be included in the grant message. Only grants per UE are used to grant the right to transmit on the UL-SCH (ie, there is no grant per UE, per RB). Therefore, the UE needs to allocate allocated resources among the radio bearers according to some rules. Unlike HSUPA, there is no UE-based transport format selection. The eNB determines the transport format based on some information (eg, channel quality feedback, reported scheduling information, and QoS information). The UE needs to follow its selected transport format.

  A common mode of scheduling is dynamic scheduling, which uses downlink assignment messages for downlink transmission resource assignment and uplink grant messages for uplink transmission resource assignment, which are usually specific Only valid for subframes of These messages are transmitted on the PDCCH using the UE's C-RNTI (Cell Radio Network Temporary Identifier). Dynamic scheduling is efficient in service types where traffic rates are intensive and dynamic, such as TCP.

  In addition to dynamic scheduling, the need for a specific downlink assignment message or uplink grant message over PDCCH per subframe by allocating radio resources semi-statically to UEs over a period longer than one subframe Persistent scheduling that can avoid this is defined. Persistent scheduling is useful for services such as periodic quasi-static VoIP with small data packet size. For this reason, compared with the case of dynamic scheduling, the overhead of PDCCH falls significantly.

<Logical Channel Priority Determination (LCP) Procedure>
For the uplink, the process by which UEs generate MAC PDUs to transmit using assigned radio resources is well standardized. It is designed so that the UE meets the QoS of each configured radio bearer so that it is optimal and consistent between different UE implementations. Based on the uplink transmission resource grant message carried on the PDCCH, the UE needs to determine the amount of data for each logical channel included in the new MAC and to allocate space for the MAC control element.

  When configuring a MAC PDU with data from multiple logical channels, the simplest and most intuitive method is based on absolute priority, in which the MAC PDU space is logically ordered in descending order of logical channel priority. Assigned to a channel. That is, in the MAC PDU, data from the logical channel with the highest priority is provided first, and then data from the logical channel with the next highest priority is provided, and continues until there is no MAC PDU space. The method based on absolute priority is very simple from the viewpoint of UE implementation, but data from logical channels with low priority may be lost. This omission means that data from a logical channel with a low priority cannot be transmitted because data from a logical channel with a high priority occupies the entire MAC PDU space.

  In LTE, a priority bit rate (PBR: Prioritized Bit Rate) is defined for each logical channel, data is transmitted in order of importance, and lack of data with low priority is avoided. PBR is the lowest data rate guaranteed for a logical channel. Even when the priority of the logical channel is low, PBR is guaranteed by at least the allocation of a small MAC PDU space. For this reason, the problem of omission can be avoided by using PBR.

  The configuration of MAC PDU by PBR consists of two ranges. In the first range, each logical channel is provided in descending order of logical channel priority, but the amount of data from each logical channel included in the MAC PDU corresponds to the configured PBR value of that logical channel. The amount to be limited from the beginning. After all logical channels have been provided up to their respective PBR values, the second range is executed if there is room in the MAC PDU. In the second range, each logical channel is again provided in descending order of priority. The major difference in the second range when compared to the first range is that MAC PDU space is allocated to each lower priority logical channel only when there is no more data to transmit on all higher priority logical channels. It is possible.

  The MAC PDU may include a MAC CE as well as a MAC SDU from each configured logical channel. Except for the padding BSR, the MAC CE controls the operation of the MAC layer and therefore has a higher priority than the MAC SDU from the logical channel. Thus, when a MAC PDU is configured, it is included first if a MAC CE is present, and the remaining space is used for MAC SDUs from the logical channel. If another space remains and is large enough to contain the BSR, the padding BSR is triggered and included in the MAC PDU.

  The prioritization of logical channels is standardized in Section 5.4.3.1 of Non-Patent Document 3, for example, which is incorporated herein. It is up to the UE implementation whether to determine the MAC PDU that includes the MAC control element when the UE is requested to send multiple MAC PDUs in one TTI.

<Buffer status report>
The buffer status report (BSR) from the UE to the eNodeB is used to support uplink resource allocation, that is, uplink scheduling by the eNodeB. For the downlink, the eNB scheduler clearly knows the amount of data delivered to each UE, but for the uplink direction, the scheduling decision is made at the eNB and the data buffer is sent to the UE. Thus, in order to indicate the amount of data that needs to be transmitted on the UL-SCH, a BSR needs to be sent from the UE to the eNB.

  For LTE, the MAC control element of the buffer status report is either a long BSR (with four buffer size fields corresponding to LCG ID # 0-3) or a short BSR (one LCG ID field and one corresponding buffer size field) With a). The buffer size field indicates the total amount of data that can be used across all logical channels of the logical channel group, and is indicated by the number of bytes encoded as an index of different buffer size levels (No. 3 of Non-Patent Document 3). See also Section 6.1.3.1 (incorporated herein)).

  Whether a short or long BSR is transmitted by the UE depends on the transmission resources available in the transport block, the number of logical channels with non-empty buffers, and whether a specific event is triggered at the UE . A long BSR reports the amount of data for the four logical channel groups, while a short BSR indicates the amount of data buffered only for the logical channel group with the highest priority.

  The reason for introducing the concept of logical channel group is that although the UE can set five or more logical channels, the buffer status is reported for each logical channel because the signaling overhead becomes too large. Therefore, the eNB assigns each logical channel to a logical channel group. Preferably, logical channels having the same / similar QoS requirements are allocated within the same logical channel group.

  If the uplink resource is not allocated to include the BSR in the transport block when the BSR is triggered, the UE sends a scheduling request (SR) to the eNodeB and is allocated the uplink resource to transmit the BSR. Like that. A single-bit scheduling request is transmitted on a physical uplink control channel (PUCCH: Physical Uplink Control Channel) (Dedicated Scheduling Request (D-SR), or by executing a random access procedure (RACH), Requests allocation of uplink radio resources for transmitting BSR.

<Other MAC control elements>
The MAC control element is used for MAC level peer-to-peer signaling.

  In LTE, another MAC control element is defined. These MAC control elements may be related to uplink transmissions or downlink transmissions.

  The Power Headroom Report (PHR) MAC control element is used to report the power headroom available to the UE, and then the uplink bandwidth per subframe available to the UE at the base station. Used to determine the width. These elements are provided in the uplink to a scheduling node (eNB), which allows scheduling of uplink transmission resources for various UEs and avoids allocation of resources to users that cannot be used due to power limitations. Currently, PHR can only be transmitted in subframes where the UE has an uplink transmission grant, i.e. subframes with uplink data transmission.

  The activation / deactivation MAC control element is used to activate / deactivate the secondary serving cell that provides additional resources to the resources of the SCell, ie, the primary serving cell. To enable reasonable UE battery consumption when carrier aggregation is configured, SCell activation / deactivation mechanisms are supported. When one or a plurality of SCells are configured in the UE, the eNodeB may activate and deactivate the configured SCell. Activation / deactivation does not apply to PCell. The MAC CE carries a bitmap for SCell activation and deactivation, while a bit set to 1 represents activation of the corresponding SCell, while a bit set to 0 indicates deactivation. To express. Bitmaps allow SCells to be individually activated and deactivated, and a single activation / deactivation command can activate / deactivate a subset of SCells.

  A Cell Radio Network Temporary Identifier (C-RNTI) MAC control element allows a UE to transmit its own C-RNTI in a random access procedure for contention resolution.

  The UE contention resolution identity (UE Contention Resolution Identity) MAC control element is an uplink CCCH (command control channel) transmitted by the UE in a random access procedure for contention resolution when the UE does not have C-RNTI. ) Is used by the eNodeB to transmit.

  The DRX command MAC control element is used by the eNodeB to send a downlink PRX command to the UE.

  The timing advance command MAC control element is used by the eNodeB to align the uplink timing by sending a timing advance command to the UE.

  The MBMS dynamic scheduling information MAC control element is transmitted for each MCH in order to notify the UE corresponding to the MBMS of scheduling of data transmission on the MTCH.

  For details regarding the above-mentioned MAC control element, refer to Section 6.1.3 of Non-Patent Document 7 (incorporated herein). One special LCID is assigned for each type of MAC control element.

<L1 / L2 processing>
FIG. 4 exemplarily shows a data flow of an IP packet up to a physical layer through a link layer protocol. The figure shows that each protocol sublayer adds its own protocol header to the mapping of transport blocks on the subframe as well as the data unit. A transport block (TB) represents a MAC PDU mapped to the physical layer.

  The mapping of transport blocks to subframes in LTE is performed in so-called transmission time intervals (TTI). In general, when the transmitter and receiver operate with single input single output (SISO), ie, one antenna, one transport block is mapped to one subframe in one TTI. In the case of MIMO / MISO (multiple input multiple output / multiple input single output), two codewords corresponding to two transport blocks may be mapped to physical resources in one TTI. In general, more than two transport blocks are considered for mapping.

The L2 functions of LTE are summarized in the table below.

  In LTE, the RLC layer performs PDCP PDU concatenation / division.

  If the transmitter knows the transport block (TB) size, the MAC layer performs logical channel priority determination (LCP) and each RLC entity should transmit (to the lower or MAC / physical layer) Determine the amount of data to be provided. Each RLC entity provides one RLC PDU that includes one or more RLC SDUs. For each RLC SDU ending with an RLC PDU, a corresponding L field (length field) is added so that the receiver can extract the corresponding SDU. If the last contained RLC SDU does not fit perfectly into the RLC PDU, it is split. That is, the rest of the RLC SDU will be transmitted in subsequent RLC PDUs. This is done regardless of whether the first (last) byte of the RLC PDU corresponding to the first (last) byte of the RLC SDU is specified by the “framing information” flag (2 bits) in the RLC header. . Apart from this, no overhead is added by the division. An RLC sequence number (SN) is added to the RLC PDU header to restore the original order of data and detect loss.

  The MAC multiplexes RLC PDUs with different logical channel identifiers (LCIDs) and adds the LCID and L fields to the corresponding subheaders. A high level diagram of the transport block structure is shown in FIG. In recent years, 3GPP has started research and work on fifth generation systems under the name of New Radio (NR). NR targets very high data rates (currently up to 20 Gbit / s on the downlink and up to 10 Gbit / s on the uplink).

3GPP TS 36.211, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)" 3GPP TS 36.321, version 13.3.0 3GPP TS 36.321, version 12.4.0 3GPP TS 36.213, version 13.0.0 3GPP TS 36.322, version 13.0.0 3GPP TS 36.212, version 13.0.0 "Multiplexing and channel coding" 3GPP TS 36.321, version 13.3.0 3GPP TS 36.322, version 13.2.0

  Since the NR is targeted for very high data rates, the processing time available to both the transmitter and receiver may be very limited compared to the amount of data transmitted. . One example of minimizing the processing time of the transmitter is to minimize the necessary real-time processing. For example, in LTE, a PDCP PDU can be generated when a PDCP SDU (ie, an IP packet) becomes available. That is, the generation of PDCP PDU can be performed in non-real time. That is, it can be executed regardless of whether or not resources are currently permitted for PDCP PDUs. However, RLC and MAC PDUs can only be generated in real time (ie after receiving UL grant). Adaptation of DL / UL data SDUs to the overall allocated TB size determined by the scheduler requires partitioning, concatenation and multiplexing. For concatenation and partitioning, it is necessary to know the scheduling decision / grant size before it can be executed in order to be subject to strict real-time processing requirements. This also implies that the transmitter cannot perform any pre-processing, for example either on the RLC or MAC layer of the sub-header / header before the scheduling / grant information. Since “pre-processing” cannot be executed, a processing delay occurs upon grant reception. If RLC processing and some MAC processing can be completed in advance (for grant reception), the delay of providing MAC TB to the physical layer is much smaller compared to the above.

  Furthermore, in the MAC PDU format used in LTE, it is impossible to start encoding early before TB generation ends. In LTE, MAC PDU is an iterative process. This is because, for example, the size of the control information (header) is determined by the number of SDUs in the PDU. This iterative process takes time until the transmission of the MAC PDU can be started. Since the MAC control element (MAC CE or BSR, PHR) is added at the beginning of the MAC PDU (TB), the computation is required before the transmission of the MAC PDU to the physical layer is started. BSR computation is only possible based on the LCP results, while the PHR computation depends on the input of this value to the MAC. Therefore, pre-calculation of the MAC header is impossible, and the MAC PDU cannot be transferred to the physical layer until the entire MAC PDU is configured. For this reason, when the MAC control element is placed in front of any MAC SDU as in LTE, the MAC layer delivers only the available MAC SDU to the physical layer after the MAC control element is computed. be able to. For example, BSR computation is possible only after LCP is completed. Also, the calculation of power headroom may take some time and depends on the physical layer signal (eg, information regarding whether PUCCH is transmitted).

  In view of the above view, an object of the present disclosure is to provide a technique for improving the efficiency of layer processing.

  The above is realized by the features of the independent claims.

  Advantageous embodiments are the subject matter of the dependent claims.

  According to one aspect of the present disclosure, a data transmission node that transmits data on a wireless channel to a data reception node in a communication system, and is mapped from a third layer to a resource allocated for data transmission Receiving one second layer service data unit (SDU) and including at least one second layer SDU and at least one second layer control element disposed after any of the at least one second layer SDU A second layer processing circuit for generating a second layer protocol data unit (PDU); a second layer PDU generated by the second layer processing circuit; and a second layer PDU assigned to a resource allocated for data transmission A first layer processing circuit for mapping Data transmission node is provided.

  According to another aspect, a data receiving node for receiving data from a data transmitting node over a wireless channel in a communication system, wherein at least one second layer protocol data unit (PDU) is allocated from resources allocated for data reception. ) And a second layer processing circuit that receives and parses the second layer PDU demapped by the first layer processing circuit, and the second layer PDU includes at least one PDU A second layer processing circuit including a second layer service data unit (SDU) and at least one second layer control element following either of the at least one second layer SDU. Provided.

  According to yet another aspect of the present disclosure, a method for transmitting data over a wireless channel to a data receiving node in a communication system, wherein the data is mapped from a third layer to a resource allocated for data transmission. Receiving one second layer service data unit (SDU) and including at least one second layer SDU and at least one second layer control element disposed after any of the at least one second layer SDU Generating a second layer protocol data unit (PDU); receiving the second layer PDU generated by the second layer processing; and mapping the second layer PDU to a resource allocated for data transmission; A method is provided.

  In another aspect, a method for receiving data from a data transmission node over a wireless channel in a communication system, wherein at least one second layer protocol data unit (PDU) is de-coupled from resources allocated for data reception. Mapping and receiving and parsing a second layer PDU demapped by the first layer processing circuit, wherein the second layer PDU comprises at least one second layer service data unit (SDU) and Receiving and parsing a second layer PDU comprising at least one second layer control element following any of the at least one second layer SDU.

  Further provided is a computer readable medium storing instructions that, when executed on a computer, cause the computer to perform the steps of the method.

  Hereinafter, exemplary embodiments will be described in more detail with reference to the accompanying drawings.

FIG. 1 illustrates an example architecture of a 3GPP LTE system. 1 is an exemplary overview of the entire 3GPP LTE E-UTRAN architecture. FIG. It is the figure which showed the OSI model provided with the various layers for communication. It is the figure which showed the relationship between a protocol data unit (PDU) and a service data unit (SDU), and the exchange between layers. It is the figure which showed the outline | summary of the various functions of PDCP, RLC, and MAC layer, and showed the processing of SDU / PDU by various layers exemplarily. It is the schematic diagram which showed the process of the data by the various layers of the radio | wireless access network in the user plane of LTE. It is the schematic diagram which showed the mapping to the physical resource by modification of the pre-processing of MAC PDU and the pre-processed header. It is a schematic diagram of the example transmission side process by three layers. FIG. 6 is a schematic diagram of exemplary receiver processing by three layers when one of two MAC PDUs is lost. FIG. 4 is a schematic diagram of an exemplary transmission side process by three layers when one of two MAC PDUs is lost. It is a schematic diagram of the example receiving side process by three layers when both MAC PDU is received correctly. It is the schematic diagram which showed the example layer process of the transmission side with respect to 1st transmission. It is the schematic diagram which showed the structure of the LTE status report. It is the schematic diagram which showed the structure of the RLC status report. It is the schematic diagram which showed the example layer process of the transmission side with respect to 1st transmission using a division number. It is the schematic diagram which showed the example layer process of the receiving side with respect to 1st transmission using a division number. It is the schematic diagram which showed the example layer process of the transmission side with respect to retransmission using the (re) division number. It is the schematic diagram which showed the example layer process of the receiving side with respect to retransmission using the (re) division number. It is the schematic diagram which showed the example layer process of the transmission side with respect to the 1st transmission which supports a multiple connection. It is the schematic diagram which showed the example layer process of the receiving side with respect to the 1st transmission which supports a multiple connection. FIG. 6 is a schematic diagram illustrating exemplary layer processing on the transmission side for retransmission supporting multiple connections. FIG. 5 is a schematic diagram illustrating exemplary layer processing on the receiving side for retransmission supporting multiple connections. FIG. 2 is a block diagram illustrating the functional structure of an exemplary data transmission and data reception device. FIG. 4 is a flow diagram illustrating steps of an exemplary method performed on a transmitting side and a receiving side. FIG. 3 is a schematic diagram illustrating an exemplary structure of a user plane protocol stack of NR. FIG. 3 is a schematic diagram illustrating an exemplary MAC PDU format. FIG. 2 is a schematic diagram of a MAC PDU format including a MAC control element following a MAC SDU. FIG. 4 is a schematic diagram illustrating another exemplary MAC PDU format and an exemplary structure of a MAC subheader. FIG. 3 is a schematic diagram illustrating an example MAC PDU format that includes a MAC control element of a buffer status report. FIG. 3 is a schematic diagram illustrating an exemplary MAC PDU format that includes activation / deactivation MAC control elements. FIG. 3 is a schematic diagram illustrating an exemplary MAC PDU format for processing in both directions. FIG. 29 is a schematic diagram illustrating the MAC PDU format of FIG. 28 and a MAC subheader including a flag indicating the presence of a MAC control element and another MAC subheader. FIG. 6 is a schematic diagram illustrating still another exemplary MAC PDU format. It is a schematic diagram of a data transmission node and a data reception node. It is the flowchart which showed the data transmission method and the data reception method. FIG. 3 is a schematic diagram illustrating an exemplary PDU format including a MAC control element at the beginning and end.

  A mobile station, mobile node, user terminal, or user equipment (UE) is a physical entity in a communication network. One node may have a plurality of functional entities. A functional entity represents a software or hardware module that implements a predetermined set of functions and / or provides to other functional entities of a node or network. A node may have one or more interfaces that connect the node to a communication facility or medium that enables communication. Similarly, a network entity may have a logical interface that connects the functional entity to a communication facility or medium that enables communication with other functional entities or corresponding nodes.

  The term “radio resource” as used in the set of claims and in this application shall be broadly understood as representing physical radio resources such as time-frequency radio resources.

  The following exemplary embodiments provide improved radio interface layer processing for new radio technologies assuming 5G mobile communication systems. Currently, most details have not been agreed on for 5G mobile communication systems, so in the following, many assumptions need to be introduced in order to be able to explain the principles underlying the embodiments. However, these assumptions are to be understood as merely examples that do not limit the scope of the present disclosure. Those skilled in the art will recognize that the principles of the present disclosure as set forth in the claims may apply to different scenarios in a manner not explicitly described herein. For example, the new radio technology will evolve from the radio technology already defined for LTE (-A), but multiple changes are expected to meet the requirements of 5G mobile communication systems. As a result, as long as certain exemplary implementations of the various embodiments are equally applicable to both the new radio technology for 5G communication systems and the various implementations described with respect to the following embodiments (Rel. 10 / It is also possible to continue to reuse procedures, messages, functions, etc. that have been defined for the LTE (-A) communication system (related to 11/12/13/14, etc.).

  According to the present disclosure, the concatenation / split function is moved from the RLC layer to the MAC entity. This approach provides several advantages, for example, the terminal can pre-configure RLC PDUs and part of MAC PDUs (if transmission is performed on the uplink) before receiving UL grant It is. Thereby, processing time is reduced by pre-configuration of some of each RLC PDU and MAC PDU. The RLC layer does not have to wait for MAC scheduling decisions (carried in resource allocation by L1 / L2 signaling) and RLC PDU size specification. Thereby, the processing time in generating the transport block is shortened.

  FIG. 5A shows the main functions of the protocol layer of the transmitting side (TX) and the receiving side (RX). As shown in the figure, on the transmission side, division is performed in the MAC layer in cooperation with the RLC layer.

  FIG. 5B shows the following basic operation executed on the transmission side.

  a) RLC and / or MAC PDUs are preprocessed based on the number of PDCP PDUs. That is, the RLC layer does not concatenate PDCP PDUs. However, the RLC layer may further divide the RLC SDU (PDCP PDU), which is indicated by two results of PDCP PDU division: R1-PDU1 and R2-PDU2. Pre-processing can also be based on a “minimum (or average) grant size” that is statistically available with a certain high confidence in a given radio condition (eg, RSSI / RSRP). Therefore, on this minimum or average grant size, a pseudo LCP operates (because it works with the estimated grant size) and RLC and MAC PDUs are preprocessed accordingly. If a (real) grant is received and the LCP is operating at the MAC layer, it can be accommodated in the granted resource based on the LCP result (ie, the corresponding MAC PDU size is the corresponding LCID grant) Some of the pre-processed RLC PDUs (below size) will be provided to the physical layer. The physical layer may start processing for these immediately (ie, at time t1). In FIG. 5B, the pre-divided R1-PDU1 and R2-PDU2 with the preprocessing MAC header added can be accommodated in the permitted resources.

  b) Since pre-divided R1-PDU1 and R2-PDU2 cannot be accommodated in the permitted resources as a whole, further division of these PDUs is required by grasping the allocation size after LCP is performed . In other words, it is also necessary to divide the preprocessed PDU by the remaining grant (after the above steps) and recalculate each corresponding header. Splitting can be done at the MAC layer (for pre-processed and provided RLC PDUs) or at the RLC layer (based on LCP results, RLC recalculates header after splitting) To do). After this L2 processing, the resulting part (segment) of the MAC PDU is provided to the physical layer. The physical layer may start processing for these later (ie, at time t2).

  In FIG. 5B, two different RLC entities belong to different logical channels. Therefore, the MAC determines which of the MAC PDUs corresponding to which time point should be provided to the physical layer based on a logical channel priority determination procedure (LCP). An example of an LCP procedure is known by LTE and mentioned in the background section above. Nevertheless, the present disclosure is generally not limited to this.

  On the receiving side, the corresponding reverse steps are executed after the physical layer processing.

  a) The MAC layer performs demultiplexing based on the MAC header (basically the LCID field and length field) and provides the resulting MAC SDU to the RLC. When the MAC layer passes the MAC SDU to the RLC layer, it also maintains a split / concatenated header field. This is because segmentation and concatenation are performed by the MAC, and segment rearrangement and reassembly are performed by the RLC. For this reason, the MAC passes the split header field to the RLC. In other words, the MAC layer passes not only the MAC SDU but also a part of the MAC header related to the division / concatenation to the RLC.

  b) The RLC layer reassembles the RLC PDU segment (if present) before forwarding the entire RLC SDU to PDCP. Provision of the entire RLC SDU to PDCP is also performed separately. That is, for example, a “hole” is included where a segment is lost. This is because it has not been correctly received within a predetermined time or within a predetermined number of retransmissions. However, RLC needs to track missing PDUs and PDU segments. Because ARQ operates in RLC, any missing RLC PDUs and / or PDU segments shall be reported to the sender for possible retransmissions. Here, the ARQ tries to read the missing RLC PDU and / or PDU segment until the timer Timer1 expires. Timer1 starts when a hole is first seen (or when a subsequent / next RLC SDU is delivered to the PDCP layer). When Timer1 expires, the RLC shall notify the PDCP layer and the RRC. The RRC may take other measures, such as triggering a Radio Link Failure (RLF) procedure. In general, higher layer end-to-end protocols, such as TCP, can still handle correct delivery.

  c) The PDCP layer determines the incoming PDU received from the RLC based on the PDCP SN (or COUNT if available directly from the header, or COUNT that needs to be estimated / calculated from the SN contained in the PDCP header). It shall be deciphered. The COUNT calculation is done by adjusting the last COUNT value with the difference between the last PDCP SN value and the PDCP SN value in the just received PDCP PDU header. Here, “last” represents a past PDCP PDU successfully decoded. The PDCP waits for arrival of a “hole” from the RLC. However, if the designation from the RLC arrives (when Timer1 expires) before receiving the corresponding PDCP PDU, the PDCP SDU is provided to higher layers (including holes).

  The above method is applicable not only to AM but also to UM. When UM is applied, no retransmission is performed in the RLC layer. Nevertheless, on the receiving side, if the RLC PDU or RLC PDU segment is missing, the RLC SDU is assembled and provided to the PDCP layer.

  In the AM, if the RLC status report indicates that the RLC PDU and / or PDU segment is missing, the sending RLC may send the corresponding missing RLC PDU and the MAC layer including the appropriate header. PDU segments are provided to assist the receiver in reassembling the segments by retransmission.

  Alternatively, the RLC layer may provide the entire RLC PDU to the MAC layer even if only the corresponding RLC PDU segment is designated as missing. The RLC layer also shares details of the status report with the MAC layer (ie, the entire status report). The advantage of this approach is that the overhead of the RLC header is reduced. When retransmission is performed in the RLC layer, the RLC layer adds a split header field, which increases header overhead. To overcome this problem, the entire RLC PDU is sent to the MAC, and the MAC performs segmentation based on the status report. The RLC status report is understood by the MAC because a universal (common) sequence number is used between layers (PDCP, RLC, MAC). In this case, the MAC layer performs re-segmentation based on this understanding and the results of LCP and also includes appropriate headers to assist the receiver in reassembling the segments.

  In the above description, “MAC”, “RLC”, and “PDCP” are referred to, but these are terms used in the UMTS / LTE (−A) standard. However, the present disclosure is not limited to these standards or advanced versions thereof, and may operate regardless of the technical terms used.

  In other words, the framework is responsible for the first layer responsible for mapping / demapping data to physical resources (corresponding to the physical layer), the second layer (corresponding to MAC), and (RLC and / or PDCP). It can be considered as a protocol stack in which a corresponding third layer exists. In this case, the terms “first layer”, “second layer”, and “third layer” do not necessarily correspond to the OSI model layer.

  The reduction of the protocol stack treatment delay can be realized on the transmission side having the first physical layer, the second layer, and the third layer. However, the second layer starts from the third layer (resource allocation). Receiving pre-processed third layer PDUs (generated by the third layer without knowing) and receiving physical layer resource allocation (from the receiver in the uplink and from the inside in the downlink) To do. A header including division information may be added to the preprocessed third layer PDU (in advance in the third layer or the second layer). The third layer PDU preprocessed in this way may be provided to a plurality of third layer entities corresponding to a plurality of logical channels whose priorities may be different. Therefore, the second layer may execute a priority determination procedure. Then, in addition to the received resource allocation, the second layer may appropriately transmit the preprocessed third layer PDU including the division information at the first time t1 based on the result of the priority order determination procedure. A header before providing to the first layer as a layer header and optionally performing further segmentation of the preprocessed PDU to provide data to the first layer at time t2 after time t1 Correct the division information inside.

  Note that the third layer PDU received at the second layer may already be pre-segmented according to the ARQ status report if the third layer implements ARQ. However, this method is also applicable when the third layer does not implement ARQ. This pre-segmentation may then be performed according to some statistical measure or another rule for past assignments, but need not necessarily be performed.

  In addition, the present disclosure is advantageously applicable to dual or multiple connections. Multiple access is an operation that is configured so that multiple receiving / transmitting UEs in connected mode utilize E-UTRA and NR radio resources provided by different schedulers connected via non-ideal backhaul. Mode. In other words, with multiple connections, a layer above the third layer of the transmitter (such as a terminal) provides the same packet (IP or PDCP) that is transmitted to multiple base stations (eNBs). Since two or more base stations receive the same packet independently, the probability of correct reception by the network increases.

  The concept of multiple connections is somewhat similar to the dual connection, a promising solution being discussed in the 3GPP RAN working group as the so-called “double connection” concept. The term “dual connection” is used to describe the operation of a given UE consuming radio resources provided by at least two different network nodes connected by a non-ideal backhaul. In essence, the UE is connected to both the macro cell (macro eNB) and the small cell (secondary eNB). Further, each eNB included in the UE's dual connection may assume a different role. These roles are not necessarily dependent on the power class of the eNB and may vary between UEs. However, unlike a double connection in which different data is sent from the UE to different eNBs, the same IP / PDCP packet is transmitted on multiple links / cells in multiple connections. One of the multiple receiving eNBs functions as a master and implements a layer that performs reassembly of segments received over multiple connections. The master eNB communicates with other eNBs.

  For example, with respect to LTE, the PDCP layer assumes the reassembly function as well as other functions already performed when switching from single connection to multiple connections. ARQ may still operate at the RLC layer (in AM), but this requires the PDCP layer to share (all or part of) the details of the missing PDCP SN with the RLC layer. The PDCP layer will notify the RLC layer about the missing part of the segment. The RLC layer receiving entity will then send a status report to the RLC layer transmitting entity. Therefore, separate ARQ is not required for the RLC layer and the PDCP layer, which means single connection and multiple connection, and both ARQs can operate in the RLC layer. Alternatively, the PDCP layer can construct its own status report and send it to the sending PDCP entity. The status report shall include information regarding missing PDCP PDUs and / or PDU segments.

  In order to allow delay reduction and / or overhead reduction as described above, the present disclosure provides an efficient layer model that is implemented at the transmitter and receiver sides. This includes one or more of the following.

  Move the division to the second layer. That is, it is as close as possible to the physical layer that needs to perform real-time processing to map data (from the third layer) to physical resources. This makes it possible to prepare for data transmission on the shared channel even before the corresponding grant is received (this possibility may or may not be used for mounting the terminal). In other words, whether or not to use a preprocessed PDU at the terminal timing may depend on the implementation).

  Common control information accessed by multiple layers is adopted. Typically, in a layer model, it is assumed that each layer has access only to control information generated in that layer. Thereby, the duplication control information provided in a plurality of layers, that is, the headers of PDUs in different layers may overlap. This may be true for sequence numbers that allow reordering of received data. A common sequence number may be used for more than one layer (such as PDCP and RLC), which reduces header overhead.

  The upper layer (third layer, more specifically RLC or PDCP, etc.) supports the ARQ function. Thus, based on the third layer status report, the third layer performs PDU segmentation. Here, it is assumed that the division of the third layer PDU based on the status report may be different from the division performed on the basis of the allocation received at (second layer, more specifically MAC, etc.). Similar benefits may be realized if the third layer provides information based on the status report to the second layer, and only the second layer performs the split based on both the assignment and status reports. This approach allows both time savings (due to preprocessing) and resource savings (only the missing segment can be retransmitted by re-division).

<Layer 2 division and layer 3 pre-division for ARQ>
According to one embodiment, a data transmission node is provided that transmits data over a wireless interface to a data reception node in a communication system. In order to implement the functionality of the protocol stack layer model, the data sending node performs or does not perform ARQ retransmission according to the status report fed back from the data receiving node, and based on the segment length information included in the status report. The data to be retransmitted (if present), or a third layer processing unit (hereinafter “processing unit” can be replaced with “processing circuit”). The re-division includes adding to the divided data division control information as a header, for example. This header is also interpreted and used in the second layer and is conveniently provided to the second layer along with the third layer data unit. In this embodiment, it is assumed that the retransmission protocol is managed by the third layer, and application of independent ARQ / HARQ protocol in other layers below or above the third layer is not excluded.

  When the data transmission node receives the third layer data unit from the third layer processing unit, divides the third layer data unit based on resource allocation, and each segment and subdivision of the third layer data unit is applied And a second layer processing unit that forms a plurality of second layer data units including the division control information to be modified. The resource allocation may be received from the data receiving node or may be generated at the data transmitting node. For example, when the transmitting node is a terminal (UE), resource allocation (uplink grant) may be received from a base station, that is, a data receiving node. On the other hand, when the transmission node is a base station, a resource allocation for transmission may be generated at the base station and provided to the MAC layer. However, the present disclosure is also applicable to direct communication between terminals, between a repeater and a terminal, or between a repeater and a base station.

  Finally, the data transmission node receives one or more of the plurality of second layer data units from the second layer and provides a plurality of second layer data for resources allocated for data transmission. A first layer processing unit is provided that maps one or more of the units.

  The data transmission node may further include a fourth layer processing unit that provides a sequence number in the header. The sequence number increases with each new fourth layer SDU, i.e., IP packet, but has a predetermined maximum value so that the increase may circulate. The third layer advantageously includes a fourth layer processing unit that does not provide another sequence number, but includes a sequence number provided by the PDCP layer.

  As for LTE terminology, the first layer may be the physical layer, the second layer may be the MAC layer, the third layer may be the RLC layer, and the fourth layer may be PDCP. However, in some embodiments, the third layer may be considered a PDCP layer, and in particular for architectures that evolve on the basis of current LTE, a single mixed with both RLC and PDCP functions. You may think of it as a layer.

  FIG. 6 illustrates the processing on the transmission side according to the present embodiment in LTE technical terms. The transmitting side may be a terminal that transmits data to the base station in the uplink. However, the present disclosure is not limited to this, and the transmission side may be a terminal that transmits data to another terminal or any other node. Furthermore, the present disclosure is applicable to another node that is a base station, a relay node, or a data transmitter.

  As shown in FIG. 6, an IP packet 1 having a length of 1200 bytes is provided to the PDCP layer to form a PDCP SDU. A header including a D / C indicator that is considered to be a single bit is added to the PDCP SDU. This bit indicates whether the content of the PDCP PDU is data or control PDU. In this example, it is set for data PDUs (ie, the bit is equal to 1) and not set for control PDUs (ie, the bit is equal to 0). However, in general, setting / non-setting may be reversed. The PDCP header further includes a PDCP sequence number (SN).

  PDCP PDU1 (payload 1200 bytes) is sent to the RLC layer to form an RLC SDU. The RLC layer includes an RLC header associated with the RLC PDU. As shown, the RLC header includes another D / C flag, a P flag, and an RF flag. The D / C flag indicates whether control is carried or data is carried by the RLC PDU, while the P flag is a polling bit set to request a status report from the receiver (the counterpart RLC entity) It is. If this is not set, no status report has been requested. The RF flag is a re-segmentation flag indicating whether the RLC PDU is an entire PDCP PDU or a PDCP PDU segment. The RF value is initially set to 0, indicating that the RLC PDU is the entire PDU. Then, it is delivered to the MAC layer as part of RLC PDU1. In this example, in the case of the first transmission of the data of the PDCP PDU / IP packet, the RLC layer does not perform division and the MAC layer performs division. Therefore, for the first transmission, the RF value is always set to zero.

  In the example of FIG. 6, the transmitting MAC entity needs to split the RLC PDU based on the received grant. Furthermore, the grant sizes assumed in this example are 800 bytes and 400 bytes in two different transmission opportunities (or at least one grant waits for 800 bytes and the rest waits for another grant). For this reason, the MAC layer divides the RLC PDU corresponding to the MAC SDU. After splitting the RLC PDU, the transmitting MAC entity includes a segment offset (SO: Segment Offset) and a final segment field (LSF: Last Segment Field) of the included RLC PDU by including a split-related MAC header part in each MAC PDU. And form MAC PDUs denoted as MAC PDU1 and MAC PDU2 in FIG. MAC PDU1 contains an 800-byte payload, while MAC PDU2 contains a 400-byte payload. MAC PDU1 and MAC PDU2 are transmitted to TTI0 and TTI1, respectively. Then, TTI0 and TTI1 are multiplexed so as to be different resources (for example, different time resources). However, the present disclosure is thereby not limited to mapping two MAC PDUs to different times. In general, two or more MAC PDUs are mapped to different types of resources (eg, different frequencies or different streams of MIMO systems, orthogonal codes, etc.).

  The SO field in this example indicates the position (byte unit) of the PDU segment in the original PDU. Specifically, the SO field indicates the position in the data field of the original PDU to which the first byte of the data field of the PDU segment corresponds. The first byte of the original PDU data field is referenced by the value zero in the SO field. The LSF field indicates whether the last byte of the PDU segment corresponds to the last byte of the PDU.

  The MAC layer may include other fields in the MAC PDU1 and the MAC PDU2 such as an extension flag (E) indicating whether there are other fields following the logical channel ID (LCID) and the MAC header. A value of 1 indicates that this field is followed by at least one or more E / LCID fields. A value of 0 indicates that there is no longer an E / LCID field following this field and the next byte is the start byte of the MAC SDU. There may be several other fields or reserved fields in the header (not shown).

  According to the present embodiment, a data reception node that receives data from a data transmission node on a wireless interface in a communication system is also provided. The data receiving node demaps one or more of the plurality of second layer data units from the resources allocated for data transmission, and 1 of the plurality of demapped second layer data units. A first layer processing unit that provides one or more to the second layer processing unit. Furthermore, the data receiving node performs demultiplexing of the division control information from one or more of the plurality of third layer unit segments and the plurality of second layer data units, and together with the division control information, The apparatus further comprises a second layer processing unit that transfers a plurality of demultiplexed third layer unit segments to the third layer processing unit. The data receiving node further includes a third layer processing unit that performs rearrangement of the plurality of demultiplexed third layer segments and incorporation into the third layer unit.

  For this reason, the division information that is part of the second layer data unit (especially that can be carried in the second layer header) is also confirmed and used in the third layer. This approach therefore ignores strict layer separation on the one hand and saves overhead on the other hand, allowing efficient execution of reordering and reassembly at the third layer. This is particularly convenient when the ARQ procedure is implemented in the third layer, but is not necessarily required and does not limit the present disclosure.

  According to an exemplary embodiment, the third layer processing unit of the data receiving device is adapted to generate control data carrying a status report indicating whether or not at least one third layer unit segment has been correctly received. Further configured. The status report may include at least one of an acknowledgment or negative acknowledgment of at least one third layer data unit and / or a designation of a correctly received or missing segment of the third layer data unit. Good. An exemplary format of a status report that can be employed here can be found in Section 6.2.1.6 of Non-Patent Document 8. However, this is only an example, and the status report may have a different format and content as long as a positive and / or negative acknowledgment is possible for the third layer PDU or segment thereof.

  FIG. 7 illustrates an exemplary reception process for MAC PDU1 and MAC PDU2 received through an error-prone channel. As shown in FIG. 7, MAC PDU1 (payload 800 bytes) is correctly received, but MAC PDU2 (payload 400 bytes) is lost (cannot be decoded correctly, that is, CRC failure).

  The MAC layer performs demultiplexing of RLC PDU1 and transmits to the RLC layer. The RLC layer then performs MAC segment reassembly and reordering. The RLC receiver (RX) sends a status report indicating the correct reception of 800-1200 bytes belonging to MAC PDU 1 to the RLC transmitter (TX). RLC PDU segment reordering and reassembly is performed based on header information from the MAC layer. In particular, in the example of FIG. 7, the header information includes a segment offset and an LSF indicator. According to the D / C field of the RLC layer, it is possible to distinguish between an RLC data PDU and an RLC control PDU such as a status report.

  FIG. 8 illustrates an exemplary subsequent operation at the RLC transmitter, assuming that the transmitter is aware of the missing second MAC PDU2 segment (eg, based on a status report). As shown in FIG. 8, in this example, the RLC TX obtains the entire RLC PDU of the corresponding missing packet from the transmission buffer, and a new segmentation of 400 bytes (800-1200) indicated by the RLC status report as missing. (Subdivide) is executed. Subdivision includes attaching an appropriate RLC header. Here, the RLC header includes a segment offset indicating the position of the RLC PDU segment retransmitted by the offset (in bytes). In this example, since the missing 400 bytes 801 to 1200 are retransmitted, the segment offset SO is 801. Then, the subdivision RLC PDU corresponding to the missing 400 bytes is delivered to the MAC layer.

  The MAC layer then performs segmentation of the received RLC PDUs to form MAC PDU1 (including 200 bytes of data) and MAC PDU2 (also including 200 bytes of data). Each is sent to TTI0 and TTI1 as described above with reference to FIG. 6 for the first transmission. Of course, in general, only the MAC layer performs the partitioning as needed. Here, in this example, since the grant size is not sufficient, the MAC layer forms MAC PDU1 and MAC PDU2. If the allocation is sufficient, no division is necessary. Or, in some cases (when more than an assignment is required for one MAC PDU), concatenation is performed.

  In particular, the MAC layer reads the SO field and LSF field from the RLC header and corrects them based on the grant size. That is, in this example, the division size of 200 bytes and 200 bytes is reflected. As seen in FIG. 8, the MAC layer provides new segmentation information for each header (ie, SO = 801 and SO = 1001) of the segmented MAC PDU, but these were transmitted first ( Corresponds to the location of the new segment of data retransmitted in the RLC PDU and LSF (not subdivision). FIG. 9 shows an example in which both MAC PDU1 and MAC PDU2 of FIG. 8 are correctly received. The MAC layer delivers correctly received MAC PDU1 and MAC PDU2 to the RLC layer. The RLC layer delivers the entire PDCP PDU to the PDCP layer after performing MAC segment reordering and reassembly. The rearrangement is executed based on the sequence number (SN). As mentioned above, to save overhead, it is convenient to use only one sequence number for both the PDCP layer and the RLC layer.

  In other words, the RLC RX collects all segments of the RLC PDU (retransmitted or correctly received after the first transmission), reorders based on the MAC header information, and reassembles the RLC PDU. The reassembled PDU may then be provided to a higher layer (direct IP if PDCP or PDCP is not present) and further processed.

As described above, in the present disclosure, as shown in Table 2 below, the functions executed by different layers of the RAN protocol stack are corrected.

Hereinafter, Tables 3 to 5 show examples of headers of the layers PDCP, RLC, and MAC, respectively.

  In the above table, the length of the sequence number is exemplified as 10 bits. However, this is only an example and does not limit the present disclosure. In LTE, the length of the PDCP sequence number can be 5 bits, 7 bits, or 12 bits depending on the characteristics of the radio bearer. The length of the sequence number is a matter of system design, as will be apparent to those skilled in the art, and may be selected to have any length for purposes of this disclosure.

  As shown in FIG. 6, PDCP PDUs are sent to the RLC layer at the receiver. The PDCP, RLC, and MAC layers conveniently use generic sequence numbers that are known by all these layers. In this example, since all these layers grasp or SN is not necessarily required in the lower layer, at least PDCP sequence numbers grasped by PDCP and RLC are used.

  The RLC layer includes an associated RLC header (eg, an RF field indicating the entire PDU or PDU segment) in the RLC PDU. The RF value is initially set to 0 and is updated when the status report arrives at the RLC TX. When the transmitting side transmits the RLC data PDU, considering the possibility of retransmission, the RLC PDU is still stored in the retransmission buffer. A status report may require retransmission by the receiver. As can be seen in FIG. 6, the RLC PDU is then delivered to the MAC layer. The transmitting MAC entity then forms a MAC PDU by performing segmentation and / or concatenation on the MAC SDUs received from the higher layer (RLC).

  The size of the MAC PDU at each transmission opportunity (TTI) is determined and notified by the MAC layer itself according to the radio channel state and available transmission resources. As described in the background section, the shared channels can be allocated so that different allocations can be made in each TTI (eg, accommodation of different amounts of data by modulation and coding scheme changes for better link adaptation). On the other hand, dynamic scheduling may be applied.

  The size of each transmission MAC PDU can be different as described above. The transmitting MAC entity includes the RLC PDU / MAC SDU in the MAC PDU in the order of arrival at the MAC entity. Thus, a single MAC PDU may contain an entire RLC PDU or an RLC PDU segment because the MAC may perform not only partitioning but also concatenation depending on the size and allocated resources of each segment. If a MAC PDU includes N (N is an integer greater than 0) RLC PDUs and / or PDU segments, the MAC layer is N-1 long for every corresponding RLC PDU and / or PDU segment, respectively. It is assumed to include a field (L field). That is, one L field is included for each RLC PDU and / or PDU segment other than the last one.

  On the receiving side, as shown in FIG. 7 (the LI field is not shown because the examples of FIGS. 6 to 9 are not concatenation but division), the MAC layer knows the actual data start position. This is because, in addition to the header length, the MAC PDU length is known together with the L field. Here, it is assumed that the header length is known. For example, it may be specified in advance (for example, may be specified in the standard), or may be specified in a header field. In the above example, since the extension bit is used to indicate whether the header continues or ends, this allows the header size to be determined.

  The MAC layer performs demultiplexing of MAC PDUs without deleting the split fields (SO and LSF). The demultiplexed RLC PDU / segment is then delivered to the RLC layer. When the receiving RLC layer receives the RLC PDU segment, it first performs reordering and reassembly if received out of sequence (see also FIG. 9). One advantage of not performing reordering and reassembly at the MAC layer is reduced processing time. If one segment is missing on the receiving side, the MAC layer may not perform reassembly and reordering that would delay delivery to higher layers (RLC). In order not to delay reassembly and reordering, the MAC layer passes the split fields (SO, LSF) to the RLC layer. This is because division and concatenation are performed by the MAC layer as described above with reference to FIG. Thus, the RLC layer reads the split header field received from the MAC layer and performs reordering and reassembly as needed based on the split (eg, SO, LSF) and concatenated (eg, LI) header fields. To do. Thereby, since it is necessary for the receiving RLC layer to grasp and use the MAC layer signaling field, in this example, inter-layer interaction is required.

  Any RLC PDUs received out of sequence at the MAC layer are delivered to the upper layer (RLC). In the receiving RLC, an ARQ operation is performed to support error-free transmission (confirmation mode). The receiver provides an RLC status report indicating the missing PDU or PDU segment information for the RLC PDU to the sender so that the sender can retransmit only the missing RLC PDU.

  In response to the one or more PDU / segment missing status report, the RLC layer transmitter retrieves the entire RLC PDU of the corresponding missing packet from the transmit buffer and the RLC status report indicates Perform (re-) partitioning based on unknown segments. If re-segmentation is performed after receiving the status report, RLC changes the RF field from 0 to 1. Then, the (re) divided PDU is delivered to the MAC layer, and the RF flag is read out. Missing PDU segments or PDUs are broken down (repartitioned) into smaller segments before retransmission (done by the MAC layer), as radio conditions can be degraded during the retransmission procedure May be required. This is shown in FIG. 8, where the missing RLC PDU with a payload of 400 bytes is obtained at the RLC layer from the original 1200 bytes RLC PDU in the retransmission buffer, and a smaller payload of 200 bytes is obtained. It is further broken down (subdivided) into MAC PDUs.

<Subdivision in MAC layer>
Referring to FIG. 8, it can be seen that the overhead of RLC is slightly increased. Because the RLC transmitter performs subdivision based on the missing part of the segment, that is, based on 400 bytes long data that is not received correctly and delivered to the MAC layer after indicated by the RLC status report. is there. Therefore, RLC requires re-segmentation headers (including SO, RF, and LSF), which increases RLC header overhead.

  To reduce overhead, according to one embodiment, re-segmentation is performed at the MAC layer.

  In particular, according to the present embodiment, a data transmission node that transmits data to a data reception node over a wireless interface in a communication system is provided. The data transmission node includes a third layer processing unit that performs automatic retransmission request (ARQ) retransmission according to the status report fed back from the data reception node. The data transmission node receives the third layer data unit from the third layer processing unit, follows the status report, divides the third layer data unit based on resource allocation, and divides each segment of the divided third layer data unit. And a second layer processing unit that forms a plurality of second layer data units. In addition, there is a first layer processing unit that receives a plurality of second layer data units from the second layer and maps the plurality of second layer data units to resources allocated for data transmission.

  Therefore, the division function is all transferred to the second layer that is the layer closest to the physical layer. Based on the example of selection, this is illustrated in detail in FIG.

  The RLC layer of the transmitter has a polling bit for requesting a status report (when this embodiment is applied in AM rather than UM) and D indicating whether the RLC PDU carries payload (user) or control data A header including the / C field is added to the PDCP PDU (RLC SDU). In addition, since an RLC layer can operate | move also in non-confirmation mode, this indication is not limited to the RLC layer which performs ARQ.

  The RLC TX layer delivers the status report received from the RLC RX to the MAC layer. The MAC layer reads division information such as a sequence number (SN), SOstart, and SOend value from the status report, and executes division according to this. Therefore, the RLC TX gets the entire RLC PDU from the retransmission buffer and sends it to the MAC TX. This is shown in FIG. 10, which shows an RLC PDU that includes a data field with 1200 bytes of PDCP SDU data, rather than just 400 bytes as shown in FIG.

  Thereafter, the MAC TX layer performs partitioning based on partitioning information (eg, SOstart, SOend, SN, etc. indicated by the RLC status report and transferred to the MAC layer by the RLC layer as shown in FIG. 10). . According to this, a MAC PDU header is generated. The header of FIG. 10 includes an LCID (logical channel identifier), an E bit indicating whether another header information is present, and a segment offset indicating the start of a transport segment in the RLC PDU (which can be in bytes). And segmentation information including a last segment field (LSF) indicating whether the included RLC PDU segment is the last of the RLC PDU. As seen in FIG. 10, 801 and 1001 offsets for two segments of 200 bytes and 200 bytes, respectively, are conveyed.

  FIG. 11A shows a status report (STATUS PDU) defined in Non-Patent Document 8. The STATUS PDU consists of a STATUS PDU payload and an RLC control PDU header. The RLC control PDU header consists of D / C and CPT fields. The STATUS PDU payload begins with the first bit following the RLC control PDU header and consists of one ACK_SN and one E1, zero or more sets of NACK_SN, E1 and E2, and possibly a set of SOstart and SOend for each NACK_SN. An octet (8 bits) alignment is realized by including 1 to 7 padding bits as needed at the end of the STATUS PDU.

  FIG. 11B shows an exemplary format of the RLC status report. This exemplary status report is similar to the LTE status report illustrated in FIG. 11A and includes similar fields. The status report of FIG. 11B differs from the status report of FIG. 11A in that the PDCP sequence number is transmitted instead of the RLC sequence number.

  In particular, the status report includes a D / C field and a CPT (control PDU type) field that indicates whether the PDU is a status PDU (indicating the status PDU of the status report). PDCP ACK_SN is a 10-bit long field indicating the SN of the next unreceived RLC data PDU not reported as missing in the status report (STATUS PDU). Here, it is emphasized that the prefix “PDCP” is also applied to the status report because a common SN is used for the RLC and PDCP layers.

  Extension bit 1 (E1) indicates whether or not a set of PDCP NACK_SN, E1, and E2 continues. When set to 0, a set of NACK_SN, E1, and E2 does not continue If set, a set of NACK_SN, E1, and E2 follows.

  The negative acknowledgment SN (NACK_SN) (PDCP NACK_SN field in this example) indicates the SN of the RLC PDU (or part thereof) detected as lost at the receiving side of the AM RLC entity.

  The extension bit 2 (E2) indicates whether or not a set of SOstart and SOend continues. When set to 0, a set of SOstart and SOend does not continue for this NACK_SN and is set to 1. In this case, a set of SOstart and SOend follows this NACK_SN.

  According to Non-Patent Document 8, in Sections 6.2.2.18 and 6.2.2.19, SOstart and SOend are described as follows.

  SOstart (15 bits): The SOstart field (in conjunction with the SOend field) indicates the portion of the RLC PDU of SN = NACK_SN (NACK_SN with which SOstart is associated) detected as lost at the receiving side of the AM RLC entity. Specifically, the SOstart field indicates the position of the first byte of the RLC PDU portion in the data field of the RLC PDU in byte units.

  SOend (15 bits): The SOend field (in conjunction with the SOstart field) indicates the part of the RLC PDU of SN = NACK_SN (NACK_SN with which SOend is associated) detected as lost at the receiving side of the AM RLC entity. Specifically, the SOend field indicates the position of the last byte of the AMD PDU portion in the data field of the RLC PDU in byte units. A special SOend value “111111111111111” is used to indicate that the missing part of the AMD PDU includes all bytes up to the last byte of the AMD PDU. In other words, SOstart and SOend indicate the beginning and end of a negatively acknowledged RLC PDU segment, respectively.

<Segment number>
A segment offset, typically 30 bits long (both start and end), increases the MAC subheader overhead, especially for small segments.

  In order to suppress overhead, in this embodiment, the segment identification information is a segment number indicating the sequence number of the segment of the third layer data unit in the third layer data unit. This segment number may be used in the data PDU as shown (ie instead of the SO field). However, the segment number can conveniently replace SOstart and SOend by use in a status report (STATUS PDU).

  In one example, the MAC subheader (ie, the portion of the header associated with the split) is shortened by using a 4-bit long segment number instead of a 30-bit segment offset (15-bit SOstart and 15-bit SOend). . For this reason, the MAC layer performs division based on 4 bits indicating the segment number. According to the 4-bit segment number, a maximum of 16 segments can be identified. However, the number 4 here is for illustrative purposes only. If there are many or few segments required for the corresponding user plane layer architecture, it is also possible to do this using the maximum number of bits. The technique of this embodiment reduces overhead by conveying the segment number of each segment instead of the start and end of each segment in the RLC PDU. Overhead is typically reduced by addressing segments rather than offsets because the number of segments is definitely smaller than the number of RLC PDU bits with which the offset is associated.

  The adoption of segment numbers in the case of the transmission side is shown in FIG. In particular, FIG. 12 shows an IP packet provided to PDCP, which is provided to the RLC layer along with this header information, with the addition of a D / C field and PDCP SN. The RLC layer includes PDCP PDUs by adding its own header including D / C field and polling field. Here, since no division is performed in the RLC layer, the RF field is unnecessary. Rather, RLC PDU1 is provided to the MAC layer as a whole.

  As shown in FIG. 12, in the MAC layer, the RLC PDU is divided into two segments, segment 0 and segment 1, each including 800 bytes and 400 bytes. This division may be performed based on the allocation size. After splitting the RLC PDU, the transmitting MAC entity forms the MAC PDU by including the associated MAC header. In particular, this header was set to 0 for the length indicator (LI) indicating the length of the segment, the segment number (eg, 4 bits above), the last segment field (LSF), and the included RLC PDU Contains field R (indicating that subdivision will not continue). The LI field is necessary for concatenation where one MAC PDU includes two or more RLC PDUs. In the case of division, since the grant size is known, the receiver can grasp the size of the grant and perform the reverse operation accordingly.

Then, the MAC layer forms two MAC PDUs called MAC PDU1 and MAC PDU2 in FIG. 12 based on the division information. MAC PDU1 and MAC PDU2 are transmitted in each transmission time interval TTI0 and TTI1, respectively.

  FIG. 13 shows exemplary receiving layer processing in the case of this embodiment, and segment numbers are employed instead of segment offsets.

  As shown in FIG. 13, on the receiving side, MAC PDU1 is correctly received, while MAC PDU2 is lost. The MAC layer delivers MAC PDU1 to the RLC layer with a split header (including R, segment number, and LSF). On the other hand, the RLC layer on the receiving side transmits a status report indicating the missing 800 to 1200 bytes (that is, MAC PDU2) to the transmitting RLC entity. The RLC layer then performs reassembly and reordering of RLC segments. Here, since only the first 800-byte segment is correctly received, it is not necessary to perform reordering in this example.

  FIG. 14 shows exemplary transmission layer processing when a status report is received from the data reception side. As shown in FIG. 14, the RLC layer obtains the entire RLC PDU from the retransmission buffer (this is indicated by the 1200 bytes of PDCP SDU data contained in the RLC PDU as well as the missing 400 bytes). . Then, the MAC layer performs subdivision based on the RLC status report.

  After subdivision of RLC PDUs, the transmitting MAC entity may include the associated MAC header in each subdivision MAC PDU for each included RLC PDU with its respective length (LI), 3 bit subdivision number. , The last subdivision field (LRF), and R = 1 (indicating that subdivision continues) and form MAC PDUs in FIG. 14 designated as MAC PDU1 and MAC PDU2.

  For example, as reported in the RLC status report, if the missing segment cannot match the available grant of the corresponding LCID (after performing the LCP), the MAC layer can You may make it perform a re-division | segmentation of an unknown part. For this purpose, the MAC may identify the “repartition” of the corresponding segment of the RLC PDU, for example by using 3 bits (or more if necessary).

  In summary, the second layer processing unit indicates a sequence number of the segment of the third layer data unit in the segment of the third layer data unit, and includes a segment including a subdivision number transmitted with a smaller number of bits than the segment number The identification information is included in the header of the second layer data unit. However, this does not limit the present disclosure. The size of the segment number and the subdivision number may be the same. Another term that can be employed for “subdivision” is “subsegment”. This is a sub-segment of the segment as a result of past divisions.

  Alternatively, in FIG. 14, the segment number may be used for the segment, and the segment offset may be used for the subsegment instead of the subsegment number. This is because it is assumed that higher overhead can be accepted because re-transmission does not occur frequently.

  FIG. 15 shows reception-side layer processing at the time of reception of retransmission of MAC PDU1 and MAC PDU2 shown in FIG.

  As shown in FIG. 15, the MAC layer performs demultiplexing of MAC PDU1 and MAC PDU2, and deletes a part of each header. However, since reordering and reassembly is performed at the RLC layer, the MAC layer maintains the associated split header fields (R field, segment number, LSF, LRF, and repartition number). The RLC then performs reordering and reassembly of the MAC segment and sends the result (PDCP PDU) to the PDCP layer.

<Reordering and reassembly in the second layer>
According to another embodiment of the present disclosure, the receiving side is further modified. In particular, instead of performing reordering and reassembly at the RLC layer, the MAC layer performs reordering and reassembly. In this case, the interaction between layers is unnecessary. In this configuration, the MAC layer is also responsible for executing retransmission processing. If any part of the segment is missing, the receiving entity at the MAC layer sends a status report to the MAC TX. The MAC status report is slightly different from the RLC status report. In particular, in this status report, an LCID field for distinguishing which status report belongs to which LCID (logical channel) is provided.

  In other words, a data receiving node that receives data from a data transmitting node on a wireless channel in a communication system demaps one or more of the plurality of second layer data units from resources allocated for data transmission. A first layer processing unit providing one or more of the demapped second layer data units to the second layer processing unit, a plurality of third layer unit segments, and a plurality of second layers Performs demultiplexing of division control information from one or more of the data units and transfers a plurality of demultiplexed third layer unit segments to the third layer processing unit along with the division control information And reordering a plurality of demultiplexed third layer unit segments. And a second layer processing unit that performs the assembly of the third layer data units of the third layer unit segments demultiplexed, the. The second layer processing unit may be configured to check whether the data has been correctly received and to transmit a status report to the second layer entity on the other side. This embodiment of the receiver is particularly suitable for a receiver embodiment in which split / concatenation is performed in the second layer described above.

<Multiple / duplex connections for more eNBs and the same bearer for more links>
In the case of multiple connections, the PDCP layer distributes duplicate packets to different eNBs.

Table 7 below lists the multiple connection protocol stacks for the main functions of each layer.

  FIG. 16 shows transmission-side layer processing in the case of new transmission of the IP packet 1 according to the present embodiment that supports multiple connections.

  In particular, the first layer is a physical layer, the second layer is a medium access control (MAC) layer, and the third layer is a packet data control protocol (PDCP) layer. However, the PDCP layer and the RLC layer may be combined as one layer, or the RLC may perform a function. The third layer processing unit is configured to provide the same third layer data unit to different lower layer stacks to different base stations (or generally data receiving nodes) over the radio interface. Lower layer stacks can perform segmentation / reassembly individually and independently of each other. The lower layer stack may include a physical layer and a MAC. However, the RLC layer may still be included.

  As described above, this layer has a name different from that of the current LTE layer and may have a different function. In general, multiple connections share a single layer that receives packets from higher layers and provides multiple (two or more) copies of the packets contained in its own PDU to the lower layers of each stack. Have. Multiple stacks handle splitting and reassembly separately and independently of each other as described in any of the above embodiments, but are adaptable to their respective physical channel conditions and data reception status.

  The third layer conveniently controls the retransmission process. In the multiple connection scenario, it is not necessary for each lower layer stack on the receiving side to correctly receive and reassemble the packet. It is sufficient that one stack collecting packet segments from all other stacks can reassemble the packet. This provides a kind of diversity and improves throughput.

  As shown in FIG. 16, IP packet 1 is attached to a PDCP header on the PDCP layer, and the corresponding PDCP PDU is sent to two different base stations (here, eNB 1 and eNB 2). As described above, the base stations eNB1 and eNB2 (network nodes) each implement a protocol layer (RLC / MAC / physical layer). eNB1 passes PDCP PDU corresponding to RLC PDU1 to two segments MAC PDU1 and MAC PDU2 each including 800 bytes and 400 bytes. Since the channel quality may be different for different cells, the eNB 2 may adopt different divisions. For this reason, in this example, eNB2 divides RLC PDU1 into two segments MAC PDU1 and MAC PDU2 that include 500 bytes and 700 bytes, respectively. The RLC layer may further bear the ARQ function when operating in the confirmation mode. However, as described above, PDCP may control RLC retransmission. In particular, each RLC layer (for each eNB) may pass a status report to the PDCP of the master eNB, and the master eNB determines whether retransmission is necessary and the segment of the packet of interest. In response, the PDCP commands each RLC layer to perform a retransmission.

  FIG. 17 shows processing on the receiving side. As shown in FIG. 17, MAC PDU1 including 0 to 800 bytes is received by eNB1, while MAC PDU2 of 801 to 1200 bytes is lost. On the other hand, while eNB2 receives MAC PDU1 including 0 to 500 bytes, 501 to 1200 bytes are lost due to missing MAC PDU2. The PDCP layer performs centralized reordering and reassembly.

  In this embodiment, an advantage of not performing reordering and reassembly in the RLC layer is avoidance of unnecessary retransmission at the time of multiple connections. If reassembly and reordering is performed at the RLC layer, the RLC layers of both eNBs will send individual RLC status reports to the RLC TX (eNB1 RLC sends a status report of 801-1200 bytes). The RLC of eNB2 sends a status report of 501 to 1200 bytes, so far the part that is actually missing is 801 to 1200 bytes). In this case, the RLC TX may retransmit more segments than necessary, but it will be discarded by the RLC RX.

  In order to overcome this problem, the RLC layer of this embodiment works as transparently as possible, and the center reordering and reassembly functions are performed at the PDCP layer. In order to perform the reordering and reassembly, the PDCP layer needs to understand the MAC layer segment headers (SO and LSF). This is because the division is performed by the MAC. PDCP receives PDUs from the MAC layer and performs center reordering and reassembly similar to that described in the above embodiments for the RLC layer. This sends a status report that overlaps the common segment and shows only the missing part of the segment, that is, the part that is not correctly received by any eNB.

  Referring to FIG. 17, it can be seen that the MAC PDU includes the above-described division information, that is, SO and LSF. However, as in the case of the other embodiments, the division information may include a segment number and a length of an alternative segment. Further, FIG. 15 shows that PDCP SN is also used in the RLC layer to suppress overhead. However, the present disclosure is not limited to this, and generally, similar to the current LTE, separate sequence numbers may be used for the PDCP and RLC layers. As described above, the transmission efficiency may be improved by the inter-layer design. In particular, the status report is transmitted / received at a layer (RLC) below the coordination layer (third layer, PDCP) and provided to the coordination layer, and then the received segment is matched and the segment to be transmitted is determined. Convenient. Furthermore, in addition to rearrangement and reassembly, the MAC division information may be passed to the adjustment layer in order to enable retransmission adjustment.

  However, even if PDCP does not perform retransmission coordination and the segments are actually retransmitted redundantly on each link, the present disclosure may still work with a slight loss of efficiency. In FIG. 17, the PDCP RX conveniently sends a status report for the missing 801-1200 bytes. This status report is conveniently sent to both (typically multiple) eNBs, and diversity is achieved by retransmission over both links. However, the present disclosure is not limited to this, and in general, a single connection may be reestablished for the purpose of retransmission.

  As shown in FIG. 18, when receiving a status report, the PDCP TX acquires the entire PDCP PDU (1200 bytes) from the transmission buffer, and executes re-division (extraction) of 801 to 1200 bytes indicated by the PDCP status report. Thereafter, a PDU segment (subdivision PDU) of 801 to 1200 bytes is delivered to the MAC. The MAC layer of each eNB performs its own division according to the resource allocation described in the above embodiment. In this case, as seen in FIG. 18, the first MAC entity (transmitting to eNB1) takes 801-1200 bytes for two MAC PDUs (ie, 801-900 bytes of MAC PDU1 and 901-1200 bytes of MAC). Divided into PDU2). On the other hand, the second MAC entity (transmitting to eNB 2) splits 801 to 1200 bytes into a first MAC PDU 1 of 801 to 1000 bytes and a second MAC PDU 2 of 1001 to 1200 bytes.

  In general, there are alternatives. As described above, after acquiring the entire PDU from the retransmission buffer, the PDCP performs re-segmentation of the missing packet indicated by the PDCP status report.

  However, as an alternative to the above, the PDCP status report may be understood by the MAC layer. Therefore, PDCP does not perform subdivision, but passes the entire PDU to the MAC. Then, based on the PDCP status report, the MAC performs the division.

  Yet another possibility is that PDCP informs the RLC of the missing part of the segment. The RLC layer then sends a status report to the RLC TX.

  Corresponding to the above, FIG. 19 shows the reception side (network side in this example of uplink data transmission) at the time of reception of retransmission in FIG. In particular, in this example, all segments are correctly received by the MAC and demultiplexed. RLC basically passes the received segment to PDCP together with the division information received from the MAC. PDCP performs reordering and reassembly of all segments received from all nodes (here, eNB1 and eNB2) of the multiple connections.

  FIG. 20 shows a transmission device 2000 t and a reception device 2000 r that are part of the communication system 2000 and communicate on the channel 2090. In particular, as described in the above embodiment, the fourth layer processing unit 2040t, the third layer processing unit 2030t, the second layer processing unit 2020t, and the first layer processing unit 2010t execute processing of the corresponding layers. The transmitter 2050 transmits a signal mapped to a physical resource via the antenna. Correspondingly, the receiving device 2000r includes a fourth layer processing unit 2040r, a third layer processing unit 2030r, a second layer processing unit 2020r, a first layer processing unit 2010r, and a receiver that receives a transmission signal through an antenna. 2060.

  FIG. 21 illustrates one of the method embodiments according to the present disclosure. In particular, the left side shows a method executed on the data transmitting side, while the right side shows a method executed on the data receiving side.

  This transmission method is executed by the third layer and receives step 2110t for receiving the third layer SDU, based on this, for example, step 2120t for generating a PDU by adding a header, and receiving the PDU in the second layer. A step 2130t of passing may be included. Then, for the second layer process, based on the step 2140t for receiving the third layer PDU as the second layer SDU and the received assignment (in some embodiments, further a status report) Step 2150t for performing concatenation and step 2160t for delivering the PDU thus formed to the first layer may be included. The first layer process includes a step 2170t for receiving the SDU from the second layer, a step 2180t for mapping this to a physical resource, and a step 2190t for transmitting.

  In the receiver, as part of the first layer processing, after reception (2190r) is performed, data is demapped from the physical resource (2180r) and passed to the second layer (2170r). The second layer processing includes a step 2160r for receiving a PDU, a step 2150r for demultiplexing the PDU, and a step 2140r for passing to the third layer and performing reordering and reassembly (as described above). In an alternative embodiment, reordering and reassembly is also performed in the second layer). The third layer processing includes a step 2130r for receiving a PDU, a step 2120r for performing rearrangement and reassembly, and a step 2110r for delivering the reassembled packet to an upper layer.

  Further, there is an embodiment in which a retransmission mechanism is implemented in the third layer, which includes transmission of a status report on the data receiving side and step 2128t of receiving the status report on the data transmitting side. If the status report includes a negative response for some segments (2125t “yes”), a re-segmentation is performed at the third layer (or the second layer in some embodiments).

  In summary, according to an embodiment of the present disclosure, in a communication system, a data transmission node that transmits data to a data reception node over a wireless interface, the automatic retransmission request according to a status report fed back from the data reception node (ARQ) performing retransmission and re-dividing or not re-dividing the re-transmitted data based on the segment length information included in the status report including adding division control information to the data When receiving a layer processing unit and a third layer data unit from the third layer processing unit, dividing the third layer data unit based on resource allocation, and applying each segment and subdivision of the third layer data unit A plurality of second rays including division control information to be corrected to Receiving one or more of a plurality of second layer data units from a second layer processing unit and a second layer forming a data unit, and for a resource allocated for data transmission, a plurality of A data transmission node is provided comprising a first layer processing unit that maps one or more of the second layer data units.

  According to another embodiment of the present disclosure, a data transmission node that transmits data over a wireless interface to a data reception node in a communication system, wherein an automatic repeat request (ARQ) retransmission is performed according to a status report fed back from the data reception node. A third layer processing unit for performing transmission, a third layer data unit received from the third layer processing unit, following the status report and dividing the third layer data unit based on resource allocation; A second layer processing unit forming a plurality of second layer data units including each segment of the data unit; and receiving one or more of the plurality of second layer data units from the second layer and transmitting the data Multiple resources assigned to trust A first layer processing unit for mapping one or more of the second layer data units, including a data transmitting node is provided.

  According to another embodiment of the present disclosure, a data receiving node for receiving data from a data transmitting node over a wireless channel in a communication system, wherein a plurality of second layer data units are allocated from resources allocated for data transmission. A first layer processing unit that demaps one or more of the second layer data units and provides one or more of the demapped second layer data units to the second layer processing unit; Performing demultiplexing of the division control information from one or more of the three layer unit segment and the plurality of second layer data units, and demultiplexing the plurality of third layers together with the division control information A second layer processing unit for transferring the unit segment to the third layer processing unit; And a third layer processing unit for performing a rearrangement of the third layer unit segments and an assembly of the demultiplexed third layer unit segment as a third layer data unit. .

  Further, in the communication system, a method for transmitting data to a data receiving node over a radio interface, wherein automatic retransmission request (ARQ) retransmission is executed according to a status report fed back from the data receiving node, and the division control information is transmitted as data. Performing a third layer process on the retransmitted data based on the segment length information included in the status report including adding to, or not performing a third layer process from the third layer processing unit; Receiving a three-layer data unit, dividing the third-layer data unit based on resource allocation, and including a plurality of second-segment data including division control information to be modified when each segment of the third-layer data unit and subdivision are applied Second layer process to form a two layer data unit And receiving one or more of the plurality of second layer data units from the second layer and allocating the plurality of second layer data units to a resource allocated for data transmission. Performing a first layer process mapping one or more of the methods.

  And a third layer process for transmitting automatic retransmission request (ARQ) according to a status report fed back from the data receiving node; Receiving a third layer data unit from the three layer processing unit, dividing the third layer data unit according to the status report and based on the resource allocation, and comprising a plurality of second layers including each segment of the divided third layer data unit A second layer process forming a data unit and receiving one or more of a plurality of second layer data units from the second layer, and a plurality of second layers for resources allocated for data transmission. One or more of the two-layer data units Comprising a first layer processing of mappings, the method is provided.

  Furthermore, a method for receiving data from a data transmission node on a radio channel in a communication system, wherein one or more of a plurality of second layer data units are demapped from resources allocated for data transmission. And a first layer process for providing one or more of the demapped second layer data units to the second layer processing unit, a plurality of third layer unit segments, and a plurality of second layer data units. The demultiplexing of the division control information from one or more of them is performed, and a plurality of demultiplexed third layer unit segments are transferred to the third layer processing unit together with the division control information. 2-layer processing and reordering and inverse of multiple demultiplexed third layer unit segments And a third layer processing to perform assembly of the third layer data units of the third layer unit segments duplicated, a method is provided.

<MAC subheader>
The MAC PDU is a byte sequence that is byte-aligned. One MAC PDU includes at least a MAC control element and / or a MAC SDU and optionally a MAC subheader associated with padding. The MAC control element is used for signaling between the eNB and the MAC peer of the UE. Since the MAC SDU includes data from the higher layer (RLC), it corresponds to the RLC PDU. The RLC PDU contains user data from one service. The MAC PDU includes a subheader for each MAC control element and MAC SDU.

  Each subheader includes a logical channel ID (LCID). In the subheader associated with the MAC control element, the LCID refers to the control element type of each carried MAC control element. In the subheader associated with the MAC SDU, the LCID indicates identification information of the logical channel to which each RLC PDU to be carried belongs.

<User plane protocol stack>
FIG. 22 shows an exemplary structure of the user plane protocol stack. In the vertical direction, the arrangement of various data units in the third layer and the second layer is shown. The top row represents the third layer SDU, the second row represents the third layer PDU, the third row represents the second layer SDU, and the bottom row represents the second layer PDU. In the illustrated embodiment, the third layer corresponds to the RLC layer of the user plane and the second layer corresponds to the MAC layer of the user plane. Although the fourth layer is not shown, it corresponds to the PDCP layer of the user plane in the above embodiment. The third layer and the second layer are visually separated by a broken line.

  Data units are passed from the RLC layer to the MAC layer through a logical channel (LC). In FIG. 22, two logical channels having logical channel identifiers LCID1 and LCID2 are shown. Signaling and user data relating to the channel of LCID1 are indicated by a solid line frame, and data elements associated with LCID2 are indicated by a broken line frame. As can be seen in the figure, different amounts of data units may be provided through different logical channels. In the illustrated example, in the uppermost row associated with the third layer SDU, the two data units in the uppermost row corresponding to the third layer SDU belong to the first logical channel of LCID1 (the data unit is referred to as “PDCP PDU1 ”And“ PDCP PDU2 ”), on the other hand, one data unit belongs to the second logical channel of LCID2 (“ PDCP PDU1 ”). Since the third layer SDU can be identified by the corresponding logical channel, two third layer SDUs operated by two different logical channels have the same label “PDCP PDU1” in the figure. However, the present disclosure is not limited to the case illustrated in FIG. 22, and as an alternative, different logical channels may operate the same amount of data allocated to the TB. Further, only one logical channel may exist or three or more logical channels may exist.

  The fourth layer PDU (displayed as PDCP PDU1, PDCP PDU2, and PDCP PDU1) processed as the third layer SDU is transmitted from the fourth layer processing unit through the logical channels having different identifiers LCID1 and LCID2 by the third layer processing unit. Received. By adding a third layer header including a sequence number (referred to as “RLC SN”) to each of the fourth layer PDUs corresponding to the third layer SDU, the third layer processing unit respectively And a third layer PDU consisting of the third layer SDU. Then, the third layer PDU is transferred to the second layer and received as the second layer PDU. Although the third layer SDU shown in the second row is the same as the second layer PDU shown in the third row, these same data units are shown redundantly in FIG. 22 for explanation. Only.

  The second layer processing unit receives the second layer SDU from the third layer and concatenates one or more second layer SDUs with some second layer control information and possibly padding to A second layer PDU shown in the lower row is generated. In generating the second layer PDU, different data elements are concatenated. In particular, a second layer subheader is provided for each user data and control element, labeled “MAC LCID0 + L”, “MAC LCID1 + L”, “MAC LCID2 + L”, “MAC LCID P”, respectively. Such an indication indicates that the subheader carries priority determination control information corresponding to each LCID (to which priority is assigned) and length information (L). The second layer control element (indicated as “MAC CE”) may be further inserted in the padding in addition to the second layer PDU as necessary. In the figure, padding is shown at the end of the MAC PDU with a corresponding subheader (“MAC LCID P”). As a case where a corresponding subheader exists before padding, a padding BSR that can be included in a MAC PDU instead of mere padding is conceivable (see also Section 5.4.5 of Non-Patent Document 7 for padding BSR). (Incorporated herein)).

  In some LTE versions, a subheader corresponding to padding may be assigned according to the length of padding. In particular, padding is inserted at the end of a MAC PDU, unless 1 byte or 2 bytes of padding are required. If 1-byte or 2-byte padding is required, one or two MAC PDU subheaders representing padding are placed at the beginning of the MAC PDU before any other MAC PDU subheader.

  With respect to LTE terminology, FIG. 22 shows two different logical channel PDCP PDUs (representing each RLC SDU) concatenated into a single MAC PDU. In this case, after concatenating three MAC SDUs corresponding to the two logical channels and adding corresponding MAC subheaders to each, some locations remain in the allocated resources. Conveniently, one or more MAC CEs are inserted at this location. If some places remain, padding is applied. By providing each MAC subheader instead of a single MAC header for the MAC PDU, at least a partial MAC PDU can be preprocessed.

  Correspondingly, the user plane protocol stack shown in FIG. 22 and described above is an exemplary user plane protocol stack for NR. Such a user plane enables preprocessing of the third layer header and the second layer subheader. In particular, the second layer SDU associated with the second layer subheader can be delivered to the first layer before the entire TB (entire MAC PDU) is constructed. On the one hand, this can reduce processing delay.

  The advantages associated with enabling the aforementioned processing delay reduction are the result of a suitable second layer (MAC) PDU format, as provided by the embodiments of the present disclosure. Hereinafter, various configurations of the second layer PDU format will be described with reference to FIGS. In these figures, it is assumed that the second layer corresponds to the MAC layer, but the present disclosure is not limited to the case where the second layer is the MAC layer.

  FIG. 23 is a schematic diagram illustrating an exemplary second layer PDU corresponding to the user plane protocol stack described with respect to FIG. The second layer PDU includes two second layer SDUs, two second layer control elements (CEs), corresponding four second layer subheaders, and padding. Each second layer subheader is associated with each second layer SDU and each second layer control element. Each second layer subheader precedes a second layer SDU or an associated second layer control element. In the figure, this relationship is indicated by an arrow from each second layer subheader to each second layer control element or second layer SDU. 24 to 30 also use the same arrow notation to represent the relationship of the second layer subheader. In the second layer PDU format shown in FIG. 23, the second layer control element is arranged before every second layer SDU, that is, before any second layer SDU. In other words, each second layer control element precedes the second layer SDU. Padding is arranged at the end of the second layer PDU. However, in this second layer PDU format, padding is only an optional component of the second layer PDU, and only applies if the location remains in the length of the MAC PDU corresponding to the allocated physical resource It is possible that this remaining location is too small to accommodate any other MAC SDU or MAC CE to be transmitted. This is true for any second layer PDU format according to any embodiment described elsewhere in this document.

  In FIG. 23, the number of second layer SDUs and the number of second layer control elements are both two. However, the present disclosure is not limited to a specific number of second layer control elements or a specific number of second layer SDUs. Rather than proposing a specific number of second layer control elements or second layer SDUs, this figure shows the second layer subheader, second layer SDU, second layer control element, and padding in the second layer PDU. A specific order is shown.

  As described above with reference to FIG. 22, the arrangement of FIG. 23 has an advantage that each MAC CE or MAC SDU having a corresponding subheader can be individually provided to a lower layer without waiting for assembly of the entire MAC PDU. is there.

  As a disadvantage of the second layer PDU format in FIG. 23, since any second layer control element is arranged before the second layer SDU, the second layer SDU available to the second layer processing unit is used as a physical layer. Delivery is possible only after the operation of the second layer control element. However, in order to calculate several MAC CEs, it is assumed that the calculation of the priority order determination procedure is terminated. On the other hand, few MAC SDUs require little time to prepare. However, it cannot be provided to the physical layer before the calculation of MAC CE.

<Efficient signaling of MAC control element>
To address the aforementioned drawbacks, FIG. 24 shows an advantageous embodiment of a MAC PDU, where any MAC SDU precedes the MAC CE. In particular, the MAC PDU 2400 begins with a first MAC SDU 243a preceded by an associated subheader 241a. The first MAC SDU is followed by a second MAC SDU 243b with its subheader 241b. In this example, there are only two MAC SDUs, and the logical channel ID (priority order) may be transmitted in each subheader. However, in this embodiment, the MAC PDU may include three or more MAC SDUs. The MAC PDU 2400 further includes a MAC subheader 242a associated with the first MAC CE 244a, followed by a MAC subheader 242b associated with the second MAC CE 244b. The MAC subheaders 242a, 242b precede each associated MAC CE 244a or 244b. As shown, in addition to MAC CE 244a and MAC CE 244b, the respective MAC subheaders 242a and 242b are later than both MAC SDU 243a and MAC SDU 243b and their respective subheaders 241a and 241b.

  The present embodiment is not limited to the case where there are two MAC CEs. There may be only one MAC CE, or three or more. Furthermore, although the case where the number of MAC CEs is equal to the number of MAC SDUs is shown in the figure, the number of MAC CEs may be different from the number of MAC SDUs. In the MAC PDU according to the present embodiment, the MAC CE may be less than the MAC SDU, or the MAC CE may be more than the MAC SDU. It is a feature of this embodiment that any MAC CE and any MAC subheader associated with it is after the MAC PDU and the subheader associated therewith. Optionally, padding 245 may be added. When all resources of TB are used for MAC SDU, MAC CE, and each MAC subheader, padding may be omitted.

  In general, even after mapping MAC SDUs and MAC CEs with their respective MAC subheaders, free resources remain in resources allocated for transmission, and these free resources can be further used by MAC CE or MAC. Padding is inserted when the SDU is not sufficiently transported.

  Therefore, the data transmission node that transmits data to the data reception node on the wireless channel in the communication system 3100 may reduce the processing delay by generating the MAC PDU illustrated in FIG. In particular, such a node may correspond to the device 3100t shown in FIG. 31, and includes a second layer processing unit 3120t and a first layer processing unit 3110t. The second layer processing unit 3120t receives from the third layer processing unit 3130t at least one second layer service data unit (SDU) that is mapped to a resource allocated for data transmission, and receives a second layer PDU. Suitable for generating. The second layer PDU generated by such a second layer processing unit includes at least one second layer SDU received from the third layer and at least a later one of the at least one second layer SDU. One second layer control element. The first layer processing unit 3110t is suitable for receiving the second layer PDU generated by the second layer processing unit and mapping the second layer PDU to resources allocated for data transmission.

  On the other hand, in the communication system 3100, a receiving node that receives data from a data transmission node on a wireless channel may reduce the processing delay by receiving and processing the MAC PDU illustrated in FIG. In particular, such a node may correspond to the device (data receiving node) 3100r shown in FIG. 31, and includes a first layer processing unit 3110r and a second layer processing unit 3120r. Here, the first layer processing unit 3110r is suitable for demapping at least one second layer protocol data unit (PDU) from the resources allocated for data reception. Furthermore, the second layer processing unit 3120r is suitable for receiving and parsing the second layer PDU demapped by the first layer processing unit. The second layer PDU received and parsed by such a second layer processing unit includes at least one second layer SDU transferred to the third layer processing unit 3130r included in the data receiving node 3100r, and the at least one And at least one second layer control element after any one of the second layer SDUs.

  The second layer PDU generated by the second layer processing unit of the data transmitting node and the second layer PDU received and parsed by the second layer processing unit of the data receiving node corresponding thereto are at least one second Conveniently, it further includes each second layer subheader associated with each layer SDU and each second layer subheader associated with each at least one second layer control element. As described above, by providing a plurality of MAC subheaders instead of a single MAC header in the MAC PDU, a part of the MAC PDU, not the entire MAC PDU, can be transferred to the lower layer. On the other hand, this reduces the delay because part of the MAC PDU can be processed earlier by the lower layer.

  In some systems, the MAC CE and / or SDU subheader may not be required. In systems such as LTE, the subheader may typically include a channel type designation and a length designation. Channel type designation can help to prioritize specific MAC PDU parts. The length designation specifies the length of the corresponding data part such as the length of the MAC SDU and / or MAC CE. However, in some systems, the MAC SDU may have a predetermined length or a length set by another method, and in any case, length specification may not be necessary.

  FIG. 25 shows an example of a MAC SDU sub-header format similar to the format known by the current LTE standard (see also Section 6.2.1 of Non-Patent Document 7 (incorporated herein)). )). FIG. 25 shows a MAC PDU having the same format as shown in FIG. 24, and the format of the MAC subheader is exemplified by the MAC subheader associated with the MAC SDU (shown as MAC SDU2 in the figure). This MAC SDU corresponds to the MAC SDU 243b, and its associated MAC subheader corresponds to the MAC subheader 241b shown in FIG. Therefore, the MAC subheader includes a reserved bit (R), a format 2 field (F2), an extension field (E), and a logical channel ID (LCID) field. In addition, if the subheader is associated with a MAC SDU or a variable size MAC control element, it includes a length field (L) and a format field (F).

  The extension field E may be a 1-bit field. In LTE, one row of R / F2 / E / LCID is 1 octet (byte or 8 bits) long, R field is 1 bit length, F2 field is 1 bit length, E field is 1 bit length, LCID Is 5 bits long. Already in LTE, F2 = 1 means that the size of the corresponding MAC SDU or variable-size control element is larger than 32767 bytes (corresponding to a 15-bit long field) and that the subheader is not the last subheader of the MAC PDU. Show. The extension field E indicates the presence of another MAC subheader in the PDU. In particular, the value E = 1 indicates that at least one or more MAC subheaders including at least the R / F2 / E / LCID field (and possibly the corresponding SDU or CE) follow the parsing direction of the MAC PDU. . The parsing direction in LTE is assumed to be from the beginning (starting from the header) to the end of the MAC PDU. This is also true for FIG. 25, where the parsing direction is from left to right.

  In FIG. 24, such an additional octet is shown in the second line of the subheader having fields F and L. In general, if there is only one octet in the header, there is no length field L. Therefore, the length of the MAC SDU is not conveyed. In LTE, when the MAC subheader is associated with a fixed-length MAC control element, the second octet is not included in the MAC subheader. In this case, the length of the fixed-length MAC control element is grasped by the LCID that identifies the type of the MAC control element. The F field indicates the length of the L field, and may be 7 or 15 bits long in LTE (thus extending over one or two octets). Although the R field is reserved in the current LTE standard, it may be replaced with another one or more indicators in subsequent versions of the standard. In other words, in a receiver operating according to the current standard, the R field is ignored.

  As will be described later, the parsing direction may generally be the direction from the beginning of the MAC PDU to the end of the MAC PDU, or vice versa, depending on the format of the MAC PDU.

  Regarding the field of the MAC subheader in LTE, Non-Patent Document 7, section 6.2.1 can also be referred to, which is incorporated herein.

  The LCID field has 5 bits, for example LTE, and indicates the subheader type and logical channel. Alternatively, if the subheader is associated with a control element, it indicates the control element type. Here, the type of subheader means whether the subheader is a MAC CE subheader, a MAC SDU subheader, or other (for example, reservation, padding, etc.). Each MAC CE type subheader uniquely defines the MAC CE type. For example, “11101” represents short BSR, “11010” represents PHR, while “11011” represents C-RNTI, and “11111” represents padding.

  The length field L in LTE may have 7 bits or 15 bits, depending on whether the subheader is associated with a MAC control element or a MAC SDU, or the MAC SDU length or MAC control. Indicates the length of the element. In the L field, the length of the MAC SDU or MAC control element is given in bytes. Further, the format field F may be a 1-bit field indicating the length of the L field. For example, the value F = 0 may indicate that the L field has 7 bits. On the other hand, the value F = 1 may indicate that the L field has 15 bits.

  However, the present disclosure is not limited to the subheader format of the current LTE standard. The lengths and values of the E, LCID, F, and L fields are examples corresponding to one advantageous embodiment of the MAC subheader. However, the MAC subheader having a structure corresponding to an embodiment of the present disclosure may be implemented using different field lengths or variable values.

  An exemplary MAC PDU according to an exemplary embodiment of the present disclosure is shown in FIG. The format of this MAC PDU corresponds to the format of the MAC PDU shown in FIG. The MAC PDU shown in FIG. 26 includes a MAC SDU and a MAC control element, all of which are preceded by their respective MAC subheaders. At the end of the MAC PDU, padding is shown as an optional component. In this example, only one MAC control element, that is, a BSR MAC control element is shown. However, corresponding to the MAC PDU format shown in FIG. 24, the MAC control element and each MAC subheader are arranged after each MAC SDU (MAC SDU1 and MAC SDU2 in the figure) and each MAC subheader. Although not shown, each MAC SDU included in the MAC PDU and each MAC SDU of each MAC SDU are followed by a different type of MAC control element and its associated subheader instead of the BSR MAC control element. Also good. For example, the MAC control element may be a power headroom report, a BSR (short BSR, long BSR, or incomplete BSR), or C-RNTI. Thus, the second layer control element is either a buffer status report, C-RNTI, and power headroom report, and each second associated with any buffer status report, C-RNTI, or power headroom report. The layer subheader is arranged after each of at least one second layer SDU.

  In the MAC PDU according to the embodiment shown in FIG. 24, the MAC CE (eg, BSR MAC CE and PHR MAC CE) and their associated MAC subheaders are always placed after the MAC SDU, while the MAC SDU and each The associated MAC subheader is located at the beginning of the MAC PDU corresponding to the TB. Therefore, the beginning of the MAC PDU does not depend on the MAC CE. For example, if the MAC CE is a BSR, it does not depend on the overall LCP result, and the calculation of the PHR depends on the physical layer that inputs this value to the MAC. This independence allows the first MAC PDU to be sent to the first layer (physical layer) processing unit (when the first MAC SDU is ready) even before the MAC PDU is fully configured. it can. Thus, the second (MAC) layer can start forwarding the packet to the first (physical) layer when the first second layer SDU is ready, and the second layer processing unit can There is no need to wait until the entire second layer PDU is assembled before transferring packets belonging to the second layer PDU to the lower layer. This is effective in reducing transmission processing delay, and the transmission side, that is, the data transmission node, can use more processing time for the calculation of BSR and PHR. This is because both the BSR MAC control element and the MAC PHR control element are positioned at the end of the TB, that is, after the MAC SDU included in the MAC PDU.

  The advantage of using the MAC PDU format shown in FIGS. 24 and 26 and the corresponding MAC subheader structure shown in FIG. 25 is that most MAC subheaders and MAC SDUs except the last one to be split can be preprocessed. is there. However, although such a MAC PDU format is easy to handle at the transmitter, at the receiver a specific type of MAC CE, ie, activation / deactivation MAC CE and UE in the downlink (sent from eNB to UE) It may be important to receive and process the contention resolution MAC CE or C-RNTI in the uplink (from UE to eNB) as quickly as possible. Therefore, in LTE, the MAC CE is placed before any MAC SDU of the MAC PDU mainly for this reason.

  Early processing of certain types of MAC control elements (activation / deactivation MAC CE in DL and UE contention resolution MAC CE or C-RNTI in UL) can be realized by one embodiment of the present disclosure shown in FIG. is there. In the illustrated MAC PDU, the MAC control element and its associated subheader are located at the beginning of the MAC PDU, and in this case the MAC control to which the MAC subheader is associated (in the parsing direction from the beginning to the end of the MAC PDU). Precedes the element. In particular, the illustrated MAC control element is an activated / deactivated MAC CE. The activation / deactivation MAC CE precedes any MAC SDU and any MAC subheader associated with the MAC SDU. In the figure, two MAC SDUs and their associated MAC subheaders are shown. However, this embodiment of the present disclosure is not limited to the number of MAC SDUs being two. As an alternative to this, only one MAC SDU may exist, or three or more MAC SDUs may be included in the MAC PDU. The illustrated MAC control element is an activation / deactivation CE, but as an alternative or addition to this, the UE SDU is preceded by any MAC subheader associated with the beginning of the MAC SDU, ie, the MAC SDU and MAC SDU. The tension resolution MAC CE and its associated subheader or C-RNTI and its subheader may be arranged. As shown in the figure, the MAC SDU of this embodiment may be terminated with padding as necessary.

  In other words, the MAC CE is placed before or after the MAC SDU when assembling the MAC PDU, depending on its type. The MAC CE type may be defined in each MAC CE subheader (eg, in the LCID field).

  Different types of MAC CE may be included in the MAC PDU, one of which is conveniently located at the beginning of the MAC PDU, ie before the MAC SDU, and the other type at the end of the MAC PDU, ie Conveniently placed after the MAC SDU. Therefore, in an exemplary embodiment of the present disclosure, in addition to at least one second layer control element disposed after the second layer SDU, a second layer control element disposed before the second layer SDU is provided. The second layer PDU further includes. A second layer subheader associated with a second layer control element placed before any second layer SDU is further included and placed before each first second layer control element of the second layer PDU. May be.

  An example of the MAC PDU format according to this embodiment is shown in FIG. At the beginning of the MAC PDU, there is a MAC CE or C-RNTI MAC CE, which is preceded by a subheader associated with this C-RNTI MAC CE. After the C-RNTI MAC CE, two MAC SDUs are included in the MAC PDU, preceded by a MAC subheader associated with each. However, the present disclosure is not limited to the number of second layer SDUs being two, and there may be one or more second layer control elements. The last MAC SDU is followed by another MAC CE, preceded by its associated MAC subheader. In the illustrated example, this MAC CE is a BSR MAC CE. However, the present disclosure is not limited to the MAC CE before any MAC SDU being a C-RNTI MAC CE, and is not limited to the MAC CE following any MAC SDU being a BSR MAC CE. Instead of C-RNTI, for example, an activation / deactivation MAC CE may exist, and instead of BSR MAC CE, for example, a MAC PHR control element may exist. Furthermore, two or more MAC CEs may be placed before and / or after any MAC SDU instead of one MAC CE placed before and after each MAC SDU. Good. Optionally, after the MAC CE located after each MAC SDU, padding is included at the end of the MAC PDU. The present disclosure is not limited to the CE currently defined by LTE, but can be applied to any CE in any system. In general, CEs that require long computation time or input from other layers can be conveniently located at the end of a MAC PDU. On the other hand, the available CE may be arranged at the beginning of the MAC PDU.

  The MAC PDU format shown in FIG. 33 can be advantageously used in a transmitter / receiver that allows the transfer of a part of the TB as well as the transfer of the entire TB to the lower layer / upper layer. For example, the TB may be subdivided into a plurality of parts to be individual code words and provided by each CRC.

  For this reason, if MAC PDUs are split in different parts of the TB and a MAC CE such as C-RNTI MAC CE is placed at the beginning of the MAC PDU, these MAC CEs wait for the completion and transfer of the entire TB Without need, it can be processed by the physical layer in the codeword at the transmitter.

  On the receiving side, one or more of the codewords may be individually received and their respective CRCs may be checked. The physical layer may then forward each correctly received codeword to the MAC before the entire TB is correctly received. This is advantageous because the MAC CE (eg, C-RNTI) located at the beginning of the MAC PDU can be extracted from the MAC layer before the remaining TB codeword is correctly received and passed to the MAC. Because. However, if all codewords related to the TB are not correctly received, that is, if the TB has not been successfully received, the entire TB, that is, the part that has been parsed (preprocessed) such as MAC CE and MAC SDU is also discarded. .

  The above layer processing is an example. The present disclosure is also applicable to other system designs where the transport block corresponds to one codeword and is not processed in multiple individual parts.

  Thus, the receiver can process each MAC CE without having to wait for the end of the TTI. For this reason, in the case of C-RNTI MAC CE (or another MAC CE such as activated / deactivated MAC CE), preparation processing is possible.

  Accordingly, it is convenient if the data transmitting device and / or the data receiving device can generate and transmit or receive both MAC CEs positioned before and after the MAC SDU. In general, the data transmission device may be a terminal in the uplink or a base station in the downlink.

  In an embodiment of the present disclosure, a data transmission node that transmits data on a wireless channel to a data reception node in a communication system includes a second layer processing unit configured to generate different types of second layer PDUs. You may do it. This is particularly useful for generating a first type of second layer PDU that includes at least one second layer SDU and at least one second layer control element following either of the at least one second layer SDU. May be suitable. This can be further configured to generate a second type of PDU including at least one second layer service SDU and at least one second layer control element preceding any of the at least one second layer SDU. It may be.

  As described above, in a MAC PDU, some MAC control elements are conveniently placed after the MAC SDU, while other MAC control elements are conveniently placed before the MAC SDU. Therefore, an embodiment of the present disclosure generates a second layer PDU including a type switching second layer control element (type switching MAC CE), and the second layer PDU including the type switching second layer control element is generated. A second layer processing unit is provided that is configurable to indicate whether it is a first type of second layer SDU or a second type of second layer SDU. The type switching second layer control element precedes any second layer SDU and any second layer control element that is different from the type switching second layer control element. The second layer PDU further includes a second layer subheader associated with the type switching second layer control element and preceding the type switching second layer control element. The second layer subheader associated with the type switching second layer control element precedes the type switching second layer control element. However, this explicit type switching MAC CE is only an example. Such a MAC CE does not need to decide whether to generate a MAC PDU with a CE at the beginning or end. Such a determination may be made based solely on the type of MAC CE included in the MAC PDU according to some predetermined (fixed) rules.

  Furthermore, it can be generally seen that a MAC PDU may include both MAC CEs positioned before and after the MAC SDU. Further, the uplink and the downlink may be different. For example, in the downlink, the MAC CE is always positioned first (ie, precedes any SDU), whereas in the uplink, it is mapped before or after the SDU depending on the MAC CE type. It may be decided.

  In general, in the downlink, a data transmission node that transmits data on a radio channel to a data reception node in a communication system may be a base station. In the downlink, a data receiving node that receives data from a data transmitting node on a radio channel in a communication system may be a UE. As described above, in the case of uplink, the data transmission node may be a UE and the data reception node may be a base station (eNB).

  In general, a UE and / or base station may be operable as both a data transmitting node and a data receiving node. In particular, the UE may be able to generate a MAC PDU in which the CE is placed after the SDU, and may be able to receive a MAC PDU in which the MAC CE is placed first. Similarly, the base station may allow the CE to transmit the first MAC PDU as well as allow the CE to receive the last MAC PDU. However, the present disclosure is not limited to such combinations and may or may support one or both of placing MAC CE at the end or beginning of MAC PDU in both directions, depending on the type of MAC CE. It can be configured as follows. In general, the MAC CE can be included at both ends of the MAC PDU according to each type.

  In the embodiment shown in FIGS. 23-27, each MAC subheader is placed in front of a MAC SDU or an associated MAC control element. According to the arrangement of the MAC subheader in this MAC PDU, it is assumed that the MAC PDU is parsed by the receiver in the direction from the beginning to the end (the direction from left to right in FIGS. 23 to 30). Can process the MAC subheader as soon as possible. However, in some cases it may be advantageous to begin parsing the MAC PDU from the end of the MAC PDU to the beginning (from right to left in the figure). In particular, if a control element is available at the end of a MAC PDU, the receiver can process the control element early if the MAC PDU is parsed from the end.

  When the receiver parses the MAC PDU from the end (in the reverse direction), the MAC subheader associated with the MAC control element is after each control element (in other words, before each control element in the parsing direction). If placed, it can be processed early. In order to achieve early processing of MAC subheaders associated with such MAC control elements, one embodiment of the present disclosure includes at least one second layer SDU, at least one second layer control element, and a second layer SDU. And a second layer processing unit that generates a second layer PDU including a second layer subheader associated with each of the second layer control elements, wherein each associated subheader precedes at least one second layer SDU, A data transmission is provided that includes a second layer processing unit, followed by a single second layer control element, followed by each associated subheader.

  The format of such a second layer PDU is shown in FIG. In particular, this figure shows a MAC PDU that includes two MAC SDUs (MAC SDU1 and MAC SDU2). MAC SDU1 and MAC SDU2 are directly preceded by their associated subheaders. The number of MAC SDUs shown is exemplary only. As an alternative to this, only one MAC SDU may exist, or three or more MAC SDUs may be included in the MAC PDU. The MAC PDU further includes two MAC control elements (MAC CE1 and MAC CE2) following each MAC SDU and each subheader associated with the MAC SDU, and a MAC subheader associated with each of these MAC control elements. Further, the MAC PDU may include padding.

  However, if the receiver starts parsing from the end of the MAC PDU, processing of the MAC control element and each associated subheader is delayed if the padding is placed at the end of the MAC PDU, ie after any MAC control element. To do. Thus, instead of placing padding last, it may be arranged between a MAC SDU with an associated subheader and a MAC control element with an associated subheader. This positioning is also effective when the parsing is started from the end of the PDU, since the length of the padding is generally unknown, so the padding length information can be obtained in some way (eg by signaling information). This is because parsing is not possible unless it is done.

  An example of the arrangement of the padding is shown in FIG. 28. In this case, the MAC SDU2 directly precedes the padding and the MAC CE1 directly follows the padding. A subheader associated with MAC CE1 is arranged after MAC CE1, and a subheader associated with MAC CE2 is arranged after MAC CE2. This corresponds to adding a subheader to each MAC CE in the parsing direction, but here for at least all MAC CEs the reverse direction, ie the direction from the end of the MAC PDU to the beginning. The MAC SDU may be parsed in the normal direction (forward direction) from the beginning to the end of the MAC PDU.

  For example, the two MAC control elements may be BSR MAC control elements or PHR MAC control elements. The present disclosure is not limited to a MAC PDU having two MAC control elements. As an alternative to this, there may be more than two MAC control elements, or there may be one MAC control element, for example a BSR MAC control element or a PHR MAC control element.

  In order to efficiently parse the MAC PDU in a short time, it is useful if the receiver can determine whether the MAC control element is available in the MAC PDU at the initial stage of parsing. In particular, when the MAC CE is positioned at the end of the MAC PDU, such a designation may cause the receiver to start parsing the MAC CE backward from the end of the MAC PDU. Information regarding the availability of another MAC control element may be included in the MAC subheader.

  Thus, in an exemplary embodiment, as described above, the first second layer subheader constituting the second layer PDU indicates whether the second layer PDU includes at least one second layer control element. Includes an indicator.

  Or all the 2nd layer subheaders which comprise 2nd layer PDU may contain the presence indicator. With this solution, the format of the subheader can be maintained regardless of the position of the SDU / CE in the PDU. In this way, it also conforms to the MAC subheader in the current LTE specification. On the other hand, regarding the use of resources, it is considered more efficient to include the presence indicator only in the first subheader of the MAC PDU.

  An example of such a presence indicator is shown in FIG. In the figure, a MAC PDU format similar to the MAC PDU format shown in FIG. 28 is shown. Therefore, at the beginning of a MAC PDU, there is a MAC subheader associated with the MAC SDU and preceding the MAC SDU, and at the end of the MAC PDU, there is a MAC subheader associated with the MAC control element and following the MAC control element. To do. For the first MAC subheader and the last MAC subheader of the MAC PDU, the structure of the MAC subheader is further shown. As already shown in FIG. 25, the MAC subheader includes a reserved bit (R), an F2 bit, an extension field (E), and an LCID. The configuration of R, F2, E, and LCID is the same as that discussed with respect to FIG. The first MAC subheader associated with the MAC SDU further includes a second octet that includes an F field and an L field. Such a second octet is not shown for the last MAC subheader shown. This subheader can be assumed to be associated with a fixed-length MAC CE whose size is known based on the LCID, but this embodiment also includes the case of a variable-size control element, in which case the second An octet and possibly a third octet must be included in the MAC subheader. Here, however, the first reserved bit is used to indicate whether or not a MAC control element exists in the MAC PDU. Here, when (at least one) MAC CE exists in the MAC PDU, it is assumed that it is arranged at the end of the MAC PDU. Thus, the presence indicator can be used to instruct the receiver to parse the MAC CE (and each respective header) in the reverse direction, ie from the end of the MAC PDU. Thereby, one of R bits included in the first MAC subheader and / or all MAC subheaders of the MAC PDU is set by the transmitter.

  For example, as shown in FIG. 29, R = 1 means that the MAC control element is available in the MAC PDU, and R = 0 means that the MAC control element is not available. In the figure, the R bits of both the first and last MAC subheaders of the MAC PDU are set to R = 1, but this is because the other subheaders have the same format and the R field is set similarly (R = 1). However, the present disclosure is not limited to the case where the R bits of all MAC subheaders are set to 1. As an alternative to this, for example, only the R bit of the first MAC subheader may be set to indicate whether the MAC PDU includes a MAC control element. In other words, it is sufficient if the R field is present in the first subheader, ie the first subheader that is parsed. However, it is possible to set all subheaders.

  FIG. 29 shows a case where the E bit of the last MAC subheader of the MAC PDU is set to 1. As described above with respect to the structure of the MAC subheader, the value E = 1 indicates that at least one MAC subheader is present in the parsing direction. Since parsing starts from the end, at least one or more MAC subheaders are identified by the MAC subheader associated with the MAC control element before the last MAC control element (corresponding to MAC control element “CE1” in FIG. 28) Is possible. Therefore, in this figure, the rightmost MAC subheader has an E field set to 1, and the corresponding MAC CE has a second subheader associated with the second MAC CE ( Means to follow (in the reverse parsing direction). In the second subheader, the E field is set to 0 because there are no more subheaders in the backward parsing direction and only padding (as an option) exists.

  Note that the parsing of the MAC PDU in FIG. 29 at the receiver starts from the first subheader of the first SDU. Since R = 1, the subsequent parsing is conveniently continued backward from the end of the MAC PDU as described above. After the MAC CE is extracted, SDU parsing may be restarted from the beginning (left side of the figure). However, this is just an advantageous example of parsing. Further, according to this MAC PDU format, it is also possible to parse the MAC CE from the end of the MAC PDU to the beginning after the SDU is first parsed.

  Accordingly, the present disclosure also provides a receiver that can start parsing a MAC PDU from the beginning if no MAC control element is available and from the end if at least one MAC control element is available. In one embodiment, the data receiving node is a second layer processing unit that receives and parses the second layer PDU, wherein the presence indicator indicates that at least one second layer control element is included in the second layer PDU. Indicates a second layer processing unit that parses the second layer PDU starting from the end of the second layer PDU. For example, the second layer processing unit of the receiver may be configured to parse by default from the beginning of the second layer PDU. For this reason, when syntax analysis is started, the presence indicator (such as a predetermined R bit in the current LTE specification) of the first subheader is evaluated. If the value of the R bit is R = 1, indicating that the MAC control element is included in the MAC PDU, depart from the default setting and parse the MAC PDU from the end. Note that the use of reserved bit R is an advantageous option for providing a presence indicator that indicates whether a MAC CE is present in the MAC PDU. However, the present disclosure is not limited to this, and the presence indicator may be introduced by another method such as provision of a longer MAC subheader. As described above, the present disclosure is not limited to the subheader format defined by LTE.

  Alternatively, the second layer processing unit may be configured to start parsing from the end of the MAC PDU by default. In this case, when parsing is started, the MAC subheader is evaluated at the end of the MAC PDU. When the R bit of this subheader is evaluated and R = 1 indicating that the MAC control element is present in the MAC PDU is detected, the parsing of the MAC PDU is continued from the end.

  If the MAC PDU is parsed from the end, the individual octets of the MAC subheader and MAC control element may be ordered in both directions. In other words, if the MAD PDU parsing is in the reverse direction, the bit ordering in the individual MAC subheaders and MAC CE that are parsed in the reverse direction may or may not be reverse. Good. However, the receiver needs to know the direction in which the receiver reads each MAC subheader and MAC control element.

  Thus, in one embodiment, includes at least one second layer SDU, at least one second layer control element, and a subheader associated with each of at least one second layer SDU and at least one second layer control element. A second layer processing unit for generating a second layer PDU, wherein at least one second layer SDU is preceded by each related subheader, and at least one second layer control element is followed by each related subheader. A transmitting node including a processing unit is disclosed.

  The MAC PDU format shown in FIGS. 28 and 29 implies advantages associated with both the receiver and the transmitter. The receiver can parse the MAC PDU from the end and process the MAC CE (if present) at high speed.

  On the other hand, since the MAC CE is arranged after the MAC SDU, the transmitter can take more processing time due to the calculation of the MAC CE.

  Another exemplary embodiment of the present disclosure is shown in FIG. This figure shows a PDU format in which the MAC control element is placed after the MAC SDU, while the MAC subheader associated with the MAC control element is placed before the MAC SDU. In particular, the illustrated MAC PDU includes two MAC SDUs (SDU1 and SDU2), each preceded by their associated subheader. In addition, the MAC PDU includes two MAC control elements each associated with a MAC subheader. However, the MAC subheader associated with the MAC control element is placed in front of the MAC SDU (all in the MAC PDU) at the beginning of the MAC PDU, instead of being placed directly in front of the associated MAC control element. In other words, MAC SDUs and their associated subheaders are preceded by a MAC subheader associated with the MAC control element, followed by the respective MAC control element itself. This is because the MAC CE is arranged after an arbitrary SDU and each header, and further in this example, after padding. In the illustrated example, the MAC subheader of MAC CE1 precedes the MAC subheader of CE2, which precedes the MAC SDU1, MAC SDU2, and subheaders associated with both MAC SDUs. Further, although the MAC CE1 subheader precedes the MAC CE2 subheader, the MAC control element MAC CE1 follows the MAC control element CE2. This has the advantage of efficient parsing at the receiver. Since the parsing starts from the beginning of the MAC PDU, the subheader of the first MAC CE1 is read out. The parser may then “chop” (extract) the corresponding MAC CE1 from the end of the MAC PDU immediately without waiting for another parsing. Parsing is then continued from the next subheader for the second MAC CE2. After parsing this subheader, the second MAC CE2 may be chopped from the end of the MAC PDU. Similarly, if there are more than two MAC CEs, each subheader is ordered sequentially at the beginning of the MAC PDU, while the MAC CE itself is ordered backwards from the end of the MAC PDU in the same order. .

  However, the present disclosure is not limited to this particular order. Alternatively, the MAC subheader associated with the MAC control element may be arranged in the same order as the associated MAC control element. Further, the present embodiment is not limited to a MAC PDU including two MAC SDUs and two MAC control elements. The number of MAC SDUs and MAC control elements may not be two or may be different from each other. If some resources remain in the TB, padding is optionally included in the MAC PDU. In the figure, padding is arranged between the MAC SDU and the MAC control element, so that syntax analysis can be performed from both sides of the MAC PDU without having to know the padding length.

  Note that the advantages of the present disclosure are brought about by the configuration of the MAC PDU. The receiver needs to be able to parse the MAC PDU to obtain CE and SDU. The method of performing parsing is not limited to the present disclosure. For example, in the embodiment of FIG. 30 as well, the receiver may only parse the MAC PDU from beginning to end (from left to right in the figure). Nevertheless, another advantage may be realized if the receiver can parse the rest of the MAC PDU (SDU, padding) after first parsing the MAC CE.

  Furthermore, in the embodiment of FIG. 30, no presence indicator is required. This is because the presence of a specific corresponding subheader indicates the presence of the MAC CE since the header of the MAC CE is ordered at the beginning of the MAC PDU.

  In other words, according to one embodiment, each second layer subheader associated with any of the at least one second layer control element is associated with each second layer SDU and each subheader associated with each second layer SDU. Preceding. On the other hand, the second layer control element is conveniently located after any second layer SDU.

  Therefore, the sub-header associated with the second layer control element is parsed from the beginning of the second layer PDU, and the second layer control element arranged after the second layer SDU is extracted from the second layer PDU. Thus, a receiver in which the second layer processing unit is configured may be provided.

  In the subheader, the LCID indicates whether the subheader belongs to MAC CE or MAC SDU. In the telecommunications system having the PDU structure shown in FIG. 30, the receiver parses the MAC PDU from the beginning. If the subheader belongs to MAC CE, the receiver reads the MAC CE from the end of the MAC PDU. If the subheader belongs to a MAC SDU, the receiver starts processing the SDU at the beginning of the MAC PDU.

  As an advantage of the present embodiment regarding the transmission side, since the MAC CE is arranged after the MAC SDU, more processing time is required for the calculation of the MAC CE. Further, before the TB configuration is completed, the available MAC SDU can be delivered to the physical layer processing. As an advantage on the receiving side, since the related MAC header is arranged at the beginning of the TB, the MAC CE can be processed at high speed. Since it is only after the LCP is terminated that the UE knows the presence of the BSR, the BSR MAC CE MAC subheader is conveniently placed after any MAC SDU.

  As shown in FIG. 30, the MAC CE can be positioned at the end of the MAC PDU. However, this is not necessarily the case when the padding CE is inserted into the MAC PDU. According to one embodiment, the second layer PDU includes a padding buffer status report (BSR) and a second layer subheader associated with the padding BSR, the padding BSR and the second layer subheader associated with the padding BSR. Are placed after any one of the at least one second layer SDUs.

  In particular, in LTE, a so-called padding BSR can already be inserted into a MAC PDU. The padding BSR is a BSR that is not periodic and generally does not need to be included in the MAC PDU, or a trigger BSR that is included in the MAC PDU regularly or after triggering. However, even after the MAC PDU is assembled, if some of the resources allocated to the MAC PDU are free and large enough to accommodate the BSR, the “padding BSR” is added to the MAC PDU. Inserted. Such a padding BSR may have an LCID that is different from the LCID of the non-padding BSR, and is specifically designated for different types of BSRs in Table 6.2.1-2 of Non-Patent Document 7, for example. It may be different from the LCID value. Therefore, when the padding BSR is included in the MAC PDU, in FIG. 30, it is included after MAC CE1, that is, at the end of the MAC PDU together with its subheader.

  Furthermore, as shown in FIG. 32, in a communication system, there is a method for transmitting data over a radio channel to a data receiving node, wherein at least one mapped from a third layer to a resource allocated for data transmission Receiving a second layer service data unit (SDU) 3221t and including at least one second layer SDU and at least one second layer control element disposed after any of the at least one second layer SDU; Step 3222t for generating the second layer protocol data unit (PDU), Step 3211t for receiving the second layer PDU generated by the second layer processing, and mapping the second layer PDU to the resources allocated for data transmission Step 3212t, Including, a method is disclosed.

  A method for transmitting data on a radio channel to a data receiving node in a communication system, comprising: determining a type of a second layer control element included in a second layer PDU; and Generating a first type of second layer PDU or a second type of second layer PDU, depending on the type, is disclosed. In this method, the first type of second layer PDU includes at least one second layer SDU and at least one second layer control element disposed after any of the at least one second layer SDU; The second type of PDU includes at least one second layer SDU and at least one second layer control element preceding either of the at least one second layer SDU.

  A method for transmitting data to a data receiving node on a radio channel in a communication system, comprising: generating a package that forms part of a second layer PDU; and a package that forms part of a second layer PDU And the step of transferring to the first layer processing unit are applied alternately and repeatedly. Thereby, the package which comprises a part of 2nd layer PDU is transferred to a 1st layer processing unit, before the production | generation of 2nd layer PDU is completed. Such a package may be a single SDU with each MAC CE having a respective sub-header and / or associated header, or multiple SDUs.

  32, a method for receiving data from a data transmission node on a wireless channel in a communication system, wherein at least one second layer protocol data unit (PDU) is obtained from resources allocated for data reception. ), Step 3221r for receiving the second layer PDU demapped by the first layer processing unit, and step 3222r for parsing, wherein the second layer PDU is at least one second layer service. Receiving a second layer PDU and including a parsing step 3222r including a data unit (SDU) and at least one second layer control element following any of the at least one second layer SDU. Method is disclosed.

  In one embodiment of the present disclosure, a method for receiving data includes parsing a second layer PDU from the beginning of the second layer PDU (ie, from an earlier received portion toward a later received portion).

  In another embodiment, a method for receiving data parses a second layer PDU from the end of a second layer PDU until each subheader associated with the second layer CE and each second layer CE is processed. And after processing each subheader associated with the second layer CE and the second layer CE, the remaining part of the second layer PDU is parsed from the beginning to obtain the second layer SDU and the second layer SDU Processing the associated second layer control element. The advantage of this method is that the second layer control element is processed faster when the second layer PDU has the format shown in FIGS. In this case, the subheader associated with the second layer CE and the second layer CE is arranged after any one of the at least one second layer SDU, and after the subheader associated with the second layer CE and the second layer CE. Has no padding.

  For example, if the first or any second layer sub-header includes a presence indicator that indicates whether the second layer PDU includes at least one second layer control element, the method of receiving data is for the second layer PDU It may include the step of parsing the second layer PDU starting from the end. An example of such a presence indicator is the R bit in the MAC subheader associated with the first MAC SDU of the MAC PDU of FIG. Thus, after evaluating this R bit, if R = 1, the MAC control element and the MAC associated with the MAC control element are followed according to the steps of parsing the second layer PDU starting from the end of the second layer PDU. Evaluate the subheader.

  Alternatively, in an exemplary embodiment, a method for receiving data includes parsing a subheader associated with a second layer control element from the beginning of a second layer PDU and from the second layer PDU to the second layer Extracting the second layer control element located after the SDU. For example, this method is applicable to the second layer PDU having the format shown in FIG. Parsing the second layer sub-header associated with the second layer control element from the beginning of the second layer PDU and extracting ("chopping") each second layer control element includes all second layers It may be alternately performed until the control element is extracted. Then, according to the step of parsing the rest of the second layer PDU from the beginning, at least one second layer SDU and one or more second layer subheaders associated with the at least one second layer SDU You may make it parse.

<Hardware and software implementation of this disclosure>
Other exemplary embodiments relate to the implementation of the various embodiments described above through the use of hardware and software. In this connection, a user terminal (mobile terminal) and an eNodeB (base station) are provided. User terminals and base stations are configured to perform the methods described herein, and corresponding entities such as receivers, transmitters, processors, etc. are involved in these methods as appropriate.

  It is further appreciated that various embodiments may be implemented or performed using computer equipment (processors). The computer equipment or processor may be, for example, a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device. Data input / output may be coupled to these. Various embodiments may also be implemented or embodied by a combination of these devices.

  Further, the various embodiments may be implemented by software modules that are executed by a processor or performed directly in hardware. A combination of software modules and hardware implementation is also possible. The software module may be stored in any kind of computer-readable storage medium such as RAM, EPROM, EEPROM, flash memory, register, hard disk, CD-ROM, DVD, etc.

  It is further noted that individual features of various embodiments may be the subject of another embodiment, either individually or in any combination.

  It will be appreciated by those skilled in the art that many variations and / or modifications of the present disclosure are possible, as illustrated in the specific embodiments. Therefore, it should be considered that this embodiment is only an example in all respects and is not limited in any way.

  In summary, this disclosure relates to layer processing in receivers and transmitters of communication systems. This layer processing includes at least processing on the first, second, and third layers. On the transmitting side, the third layer receives the packet, adds its header, and forwards the packet to the second layer. The second layer performs the division and provides the divided data to the first layer. The first layer maps the divided data to physical resources. Partitioning is based on allocated resources. Retransmission may occur on the third layer, so that the third layer subdivides the packet according to the received feedback for a particular segment, May be provided to the lower layer. Alternatively, feedback information is provided to the second layer, and the second layer performs division in consideration of this. Correspondingly, the receiver performs reordering and reassembly in a third layer that also receives control information from the second layer.

  Furthermore, the present disclosure relates to a system and method for transmitting data from a data transmission node to a data reception node over a wireless channel in a communication system. In particular, the data transmitting node receives from the third layer at least one second layer service data unit (SDU) that is mapped to resources allocated for data transmission, and at least one second layer SDU and A second layer processing unit that generates a second layer protocol data unit (PDU) including at least one second layer control element disposed after any of the at least one second layer SDU; and a second layer processing unit And a first layer processing unit that maps the second layer PDU to the resources allocated for data transmission. The data receiving node has a first layer processing unit for demapping at least one second layer protocol data unit (PDU) from resources allocated for data reception, and a second demapped by the first layer processing unit. A second layer processing unit that receives and parses a layer PDU, the second layer PDU following either one of the at least one second layer service data unit (SDU) and the at least one second layer SDU. A second layer processing unit including at least one second layer control element.

Claims (15)

A data transmission node for transmitting data on a wireless channel to a data reception node in a communication system,
In operation, at least one second layer service data unit (SDU) that is mapped from a third layer to resources allocated for data transmission is received, and the at least one second layer SDU and the at least one A second layer processing circuit that generates a second layer protocol data unit (PDU) including at least one second layer control element disposed after any one of the second layer SDUs;
In operation, a first layer processing circuit that receives the second layer PDU generated by the second layer processing circuit and maps the second layer PDU to the resource allocated for data transmission;
A data transmission node comprising: The second layer PDU is
Each second layer subheader associated with each of the at least one second layer SDU;
Each second layer subheader associated with any of the at least one second layer control element;
Further including
The data transmission node according to claim 1. The at least one second layer SDU is disposed after each associated subheader, and the at least one second layer control element is disposed before each associated subheader;
The data transmission node according to claim 2. A second layer subheader associated with each of the at least one second layer SDU includes a presence indicator indicating whether the second layer PDU includes at least one second layer control element;
The data transmission node according to claim 3. Each second layer subheader associated with any of the at least one second layer control element precedes each second layer SDU and each subheader associated with each second layer SDU;
The data transmission node according to claim 2. The second layer PDU includes a padding buffer status report (BSR) and a second layer subheader associated with the padding BSR, and the second layer subheader associated with the padding BSR and the padding BSR includes: Disposed after any of the at least one second layer SDU,
The data transmission node according to any one of claims 1 to 5. A first type of second layer PDU includes at least one second layer SDU and at least one second layer control element disposed after any of the at least one second layer SDU;
A second type of PDU includes at least one second layer SDU and at least one second layer control element preceding any of the at least one second layer SDU;
The second layer processing circuit is further configurable to generate a second type of second layer PDU;
The data transmission node according to claim 1. The second layer processing circuit generates a first type of second layer PDU or a second type of second layer PDU according to the type of the second layer control element included in the second layer PDU. Is configurable,
The data transmission node according to claim 7. The second layer processing circuit is configured to start transferring a package constituting a part of the second layer PDU to the first layer processing circuit before the generation of the second layer PDU is completed;
The data transmission node as described in any one of Claims 1-8. A data receiving node for receiving data from a data transmitting node on a wireless channel in a communication system,
A first layer processing circuit for demapping at least one second layer protocol data unit (PDU) from resources allocated for data reception in operation;
A second layer processing circuit that receives and parses the second layer PDU demapped by the first layer processing circuit during operation, the second layer PDU comprising at least one second layer service data unit; A second layer processing circuit comprising: (SDU) and at least one second layer control element subsequent to any of the at least one second layer SDU;
A data receiving node comprising: Each second layer subheader is
Associated with each of the at least one second layer SDU;
Associated with any of the at least one second layer control element;
The data receiving node according to claim 10. A second layer subheader associated with each of the at least one second layer SDU includes a presence indicator indicating whether the second layer PDU includes at least one second layer control element;
If the presence indicator indicates that at least one second layer control element is included in the second layer PDU, the second layer processing circuit starts from the end of the second layer PDU and Parse layer PDU,
The data receiving node according to claim 11. The second layer processing circuit parses a subheader associated with a second layer control element from the beginning of the second layer PDU, and is arranged from the second layer PDU after an arbitrary second layer SDU. And configured to extract the second layer control element,
The data receiving node according to claim 11. A method of transmitting data over a radio channel to a data receiving node in a communication system, comprising:
Receiving from the third layer at least one second layer service data unit (SDU) mapped to a resource allocated for data transmission, and said at least one second layer SDU and said at least one second Generating a second layer protocol data unit (PDU) including at least one second layer control element disposed after any of the layer SDUs;
Receiving the second layer PDU generated by a second layer processing circuit and mapping the second layer PDU to the resource allocated for data transmission;
Including methods. A method for receiving data from a data transmission node over a wireless channel in a communication system, comprising:
Demapping at least one second layer protocol data unit (PDU) from resources allocated for data reception by first layer processing;
Receiving and parsing a second layer PDU demapped by the first layer processing, wherein the second layer PDU comprises at least one second layer service data unit (SDU) and the at least one first layer PDU; Receiving and parsing the second layer PDU comprising at least one second layer control element following either of the two layer SDUs;
Including methods.

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